Serological testing to inform decisions to vaccinate
Serological testing refers to testing for specific antibodies or other markers of infection or immunity. Serological testing may be recommended either before or after vaccination to assess immunity against a vaccine-preventable disease and to assist in making decisions about vaccination.
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This page was added on 06 November 2026.
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This page was updated on 12 November 2026. View history of updates
General principles
Serological testing refers to testing for specific antibodies or other markers of infection or immunity. For select vaccine-preventable diseases (VPDs), serological testing may be warranted:
- Before-immunisation: to assess for pre-existing immunity (from prior vaccination or infection), and to guide the need for vaccination and further doses. Examples include occupational screening and post-exposure serological tests. However, in many circumstances, administering further immunisation doses may be preferable to conducting serological testing.
- Post-vaccination: to assess whether a person has had an adequate response to vaccination and/or provide evidence of protection where required. This is usually performed 4–8 weeks after immunisation, as antibody titres wane over time.
Serological testing should only be used to assess for evidence of immunity if:
- A correlate of protection is published,
- A validated serological test is available, and
- The result will inform a clinical decision.
There are limitations of serological tests:
- A correlate of protection has not been established for many VPDs.1,2 Antibody assays do not always correlate with clinical protection, as they do not assess antibody functional activity or cellular immune responses.2
- Serological testing is most reliable when performed 4–8 weeks after immunisation.3 Antibody responses are highest at this point and subsequently wane over time, although clinical protection may be retained (for example, from the anamnestic response generated).
- Many commercially available tests were designed to detect IgG antibodies generated following natural infection. However, IgG titres are generally much higher after natural infection than after immunisation. Therefore, some serological tests are not sensitive enough to detect vaccine-induced immunity.
- Serological testing is invasive, may incur a cost to the patient and may be inconvenient and time-consuming, while results may not be available in a timely manner. Results may also be misinterpreted or difficult to interpret, and result in unnecessary further investigation and follow-up. Serological testing should therefore always be judiciously ordered, and in consultation with specialist services where appropriate.
- Serological testing is also unreliable if a person has recently received blood products and/or immunoglobulin, which can contain antibody from the donor.
Evidence of immunity against vaccine-preventable diseases
For most vaccine-preventable diseases, serological testing is usually not needed (or useful) if an individual has received a documented complete vaccination course or a confirmed history of natural infection. If an individual has received a full course of immunisation but subsequently has a negative serological test result, revaccination is NOT routinely required, as a negative serological test does not necessarily indicate that the person lacks clinical immunity against the disease (due to the limitations in serological testing outlined above).
However, for certain vaccine preventable diseases, serological testing may be required to verify immunity before or following vaccination; for example, following rabies vaccination, or to assess immunity following hepatitis B immunisation (particularly for clinical decision making around post-exposure prophylaxis). See Table. Appropriate evidence of long-term immunity against vaccine-preventable diseases for appropriate evidence of immunity against specific VPDs.
| Vaccine antigen | Acceptable evidence of immunity | Notes |
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| Cholera |
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| COVID-19 |
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| Diphtheria |
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| Haemophilus influenzae B (Hib) |
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| Hepatitis A |
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| Hepatitis B |
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| Human papillomavirus (HPV) |
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| Influenza |
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| Japanese encephalitis |
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| Measles |
For people born during or since 1966:
People born before 1966 are considered immune, and do not require vaccination or serological testing. |
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| Meningococcal disease |
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| Mpox |
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| Mumps |
For people born during or since 1966:
People born before 1966 are considered immune, and do not require vaccination or serological testing. |
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| Pertussis |
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| Pneumococcal disease |
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| Polio |
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| Q fever |
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| Rabies and other lyssaviruses |
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| Respiratory syncytial virus (RSV) |
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| Rotavirus |
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| Rubella |
For people born during or since 1966:
People born before 1966 are considered immune, and do not require vaccination or serological testing. |
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| Tetanus |
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| Tuberculosis |
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| Typhoid fever |
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| Varicella (chickenpox) |
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| Yellow fever |
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| Zoster (herpes zoster) |
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Acronyms used:
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Vaccines for which serological testing is recommended
Serological testing is either recommended or may be considered in specific circumstances for the following vaccines:
- Diphtheria
- Hepatitis A
- Hepatitis B
- Measles-mumps-rubella (MMR)
- Q fever
- Rabies
- Varicella
- Yellow fever
Recommendations and considerations for serological testing to inform vaccination decisions are summarised in Table. Indications for serological testing to guide the decision to vaccinate.
Special considerations for serological testing to guide vaccination in immunocompromised people
Immune responses to vaccines may be inadequate in immunocompromised people, and people who are vaccinated may remain susceptible to infectious pathogens despite vaccination.4
In addition to limitations of serological testing described above, the results of serological tests in immunocompromised individuals can be more challenging to interpret. This is because:
- The effects of different immunocompromising conditions and level of immunocompromise can vary
- Antibody levels can be depleted by immunomodulatory therapies
- Antibody levels can vary with time, depending on the nature and severity of the underlying condition, while serological testing only provides a snapshot in time
- Correlates of protection may not apply in the same way; for example, patients with functional or anatomical asplenia may require a higher antibody concentration than immunocompetent people for protection against infections due to encapsulated bacteria (such as Streptococcus pneumoniae and Haemophilus influenzae B).2
Because of these challenges, test results should be interpreted with caution and in consultation with a specialist in immunisation. The optimal timing of testing (if testing is recommended) should also be considered; conducting testing prior to commencing immunosuppressive treatment is preferred to minimise confounding or inaccurate results.
Pre-vaccination serological testing for vaccinating immunocompromised people
- Pre-vaccination serological testing is generally not recommended due to the above outlined limitations. The exception is MMR vaccine in immunocompromised people – see Table. Indications for serological testing to guide the decision to vaccinate.
- However, there may be instances where serological testing may be useful to guide the decision to vaccinate immunocompromised people with live vaccines, such as:
- People with HIV who are clinically stable, have a low or undetectable viral load and have CD4+ cell count ≥200 cells per μL;5 or
- To determine the post-exposure management of immunocompromised patients who may have been previously vaccinated against the disease.
- Pre-vaccination testing is not recommended for haematopoietic stem cell transplant recipients. All haematopoietic stem cell transplant recipients should be viewed as “never immunised” because the ablation of haematopoietic cells in the bone marrow pre-transplant eliminates most, or all, immune memory.6 The exception is for MMR vaccination, see Haematopoietic stem cell transplant: recommendations for vaccination.
Post-vaccination serological testing for vaccinating immunocompromised people
- Post-vaccination serological testing is recommended in a limited number of circumstances for immunocompromised people for some vaccines, and is specific to the immunocompromising condition and the vaccine (see Table. Indications for serological testing to guide the decision to vaccinate).
- Post-vaccination testing is not recommended for people with functional or anatomical asplenia, as they generally have similar immune responses as immunocompetent people for many routine vaccines.7 Furthermore, asplenic patients may require a higher antibody concentration than immunocompetent people for protection against some invasive infections, so serological test results may be inaccurate.2 For specific recommendations on when post-vaccination serological testing should be conducted and for which vaccines and diseases, see Table. Indications for serological testing to guide the decision to vaccinate.
| Vaccine preventable disease | General population | Immunocompromised people | Pregnant women/people and women/people planning to become pregnant | People without clear documentation of vaccination, including migrants or refugees | Healthcare workers and others at occupational risk |
|---|---|---|---|---|---|
| Diphtheria | Not routinely recommended | Not routinely recommended | Not routinely recommended | Not routinely recommended | Serological testing every 10 years is recommended for laboratory workers who may be exposed to toxigenic Corynebacterium diphtheriae in their jobs. See recommendation: People who may be exposed to diphtheria in their jobs are recommended to receive a dose of either dT or dTpa vaccine if their last dose of diphtheria-toxoid vaccine was more than 10 years ago. |
| Hepatitis A |
Pre-vaccination serological testing can be considered to confirm natural immunity in:
If serological testing is positive, vaccination is not needed. See recommendation: serological testing for hepatitis A immunity is not recommended before or after receiving hepatitis A-containing vaccine, with rare exceptions |
Follow guidance for general population | Follow guidance for general population | Follow guidance for general population | Follow guidance for general population |
| Hepatitis B |
Pre-vaccination serological testing is recommended in people at higher risk of hepatitis B, including people who inject drugs, sex industry workers and people living in communities with higher prevalence of hepatitis B. See recommendation People at higher risk of hepatitis B are recommended to have serological testing for hepatitis B before vaccination. Post-vaccination serological testing is recommended 4–8 weeks after completing the vaccine course for people at risk of hepatitis B infection. For details on who testing is recommended for, see recommendation: People at risk of hepatitis B are recommended to have serological testing 4–8 weeks after they complete the hepatitis B vaccine course. Pre-vaccination serological testing is recommended in people at higher risk of hepatitis B, including people who inject drugs, sex industry workers and people living in communities with higher prevalence of hepatitis B. See recommendation People at higher risk of hepatitis B are recommended to have serological testing for hepatitis B before vaccination. Post-vaccination serological testing is recommended 4–8 weeks after completing the vaccine course for people at risk of hepatitis B infection. For details on who testing is recommended for, see recommendation: People at risk of hepatitis B are recommended to have serological testing 4–8 weeks after they complete the hepatitis B vaccine course.
Post-vaccination serological testing is recommended for infants born to mothers with chronic hepatitis B, 3–12 months after completing the infant hepatitis B vaccine course. See recommendation: Infants born to mothers with chronic hepatitis B are recommended to have serological testing 3–12 months after they complete the infant hepatitis B vaccine course. |
Post-vaccination serological testing is recommended for immunocompromised people and others at risk of severe or complicated hepatitis B infection including people with pre-existing liver disease, haemodialysis patients or people with bleeding disorders who received the vaccine subcutaneously. Testing should be conducted 4–8 weeks after completing the vaccine course. For details on testing requirements and clinical management, see recommendation People at risk of hepatitis B are recommended to have serological testing 4–8 weeks after they complete the hepatitis B vaccine course. Pre-vaccination serological testing can be considered for immunocompromised people. See recommendation People at higher risk of hepatitis B are recommended to have serological testing for hepatitis B before vaccination. |
Routine antenatal screening of all pregnant women for hepatitis B surface antigen (HBsAg) is recommended to detect hepatitis B infection. See recommendation: Pregnant women are recommended to be screened for HBsAg |
Follow guidance for general population Serological testing may be considered if there is a possibility that the individual is not immune (ie vaccination is not documented). |
Serological testing is recommended for healthcare workers and those with frequent exposure to human tissue, blood or fluids if they have never been tested after finishing a complete course of hepatitis B immunisation. For details on testing requirements and clinical management, see recommendation: People at risk of hepatitis B are recommended to have serological testing 4–8 weeks after they complete the hepatitis B vaccine course. |
| MMR (measles, mumps and rubella) |
Serological testing for measles, mumps and/or rubella immunity may be helpful if:
See recommendation: Serological testing for immunity to measles is not recommended before or after receiving measles-containing vaccine, with rare exceptions. |
Follow guidance for the general population. Where confirmation of protection against measles after a complete course of MMR vaccination is desirable, serological testing may be conducted 4–6 weeks after the 2nd dose of MMR vaccine. Note: MMR vaccine is a live attenuated vaccine and is contraindicated for most moderately and severely immunocompromised people. |
Follow guidance for general population for measles and mumps. All women who are planning pregnancy or have recently become pregnant should be screened for rubella antibodies, irrespective of documentation of vaccination with rubella-containing vaccine and/or a previous positive rubella antibody result. See recommendation: Serological testing for immunity to rubella is recommended before or after receiving rubella-containing vaccine in certain circumstances. See recommendation: Women of child-bearing age who are seronegative for rubella are recommended to receive rubella-containing vaccine |
Follow guidance for the general population. Women of child-bearing age: Serological testing for rubella may be recommended for certain women of child-bearing age, including women born overseas, Aboriginal and Torres Strait Islander women living in rural and remote regions, and non-English speaking women. Serological testing in these populations is useful to help identify seronegative women of child-bearing age. See recommendation: Women of child-bearing age who are seronegative for rubella are recommended to receive rubella-containing vaccine |
Follow guidance for the general population. |
| Q fever | People who are being considered for Q fever vaccination are recommended to have both serum antibody testing and a Q-Vax skin test before Q fever vaccination. See recommendation: People are recommended to have both serological and skin tests before Q fever vaccination. | Not required – Q fever vaccination is contraindicated in immunocompromised people | Not required – Q fever vaccine is not routinely recommended for pregnant or breastfeeding women. | Follow guidance for the general population. | Follow guidance for the general population. |
| Rabies |
Not routinely recommended after pre-exposure prophylaxis administered intramuscularly. Serological testing is recommended in people who received pre-exposure prophylaxis by the intradermal route. The recommended timing of serological testing varies depending on the specific circumstances, including patient characteristics, level of exposure risk, vaccination history and exposure type (for post-exposure prophylaxis). See recommendations for immunisation against rabies and other lyssaviruses to determine when serological testing is needed. |
Serological testing after rabies vaccination is recommended, both after pre-exposure prophylaxis and after post-exposure prophylaxis. See recommendations for immunisation against rabies and other lyssaviruses. | Follow guidance for the general population. | Follow guidance for the general population. |
Serological testing for rabies immunity is recommended among people who have occupational risk of exposure to bat lyssaviruses in Australia or overseas. See recommendation: People with ongoing occupational exposure to lyssaviruses are recommended to receive booster doses of rabies vaccine |
| Varicella | Not routinely recommended. | Serological testing may be helpful to guide post-exposure management of immunocompromised people. |
Women who are planning pregnancy or pregnant are recommended to receive screening for varicella immunity. Serological testing should only be conducted in women without a clear history of varicella vaccination and/or varicella or zoster infection. See recommendation: Serological testing for immunity to varicella is not recommended before or after receiving varicella-containing vaccine. |
Serological testing to determine the need for vaccination may be considered if:
See recommendation: Serological testing for immunity to varicella is not recommended before or after receiving varicella-containing vaccine. |
Serological testing can be conducted to demonstrate immunity against varicella if there is an absence of evidence of immunity, ie:
See recommendation: Healthcare workers are recommended to receive 2 doses of varicella vaccine if they are not immune. |
| Yellow fever |
Not routinely recommended. Serological testing may be considered for people who may not have responded optimally to previous yellow fever vaccination (eg women who were pregnant or due to potential immunosuppression at the time of vaccination). See recommendation: People aged ≥9 months travelling to an area with a risk of yellow fever virus transmission are recommended to receive yellow fever vaccine |
Serological testing may be considered to guide decisions on the need for booster doses among certain immunocompromised people who have previously received vaccination, particularly people with HIV. See recommendation: People aged ≥9 months travelling to an area with a risk of yellow fever virus transmission are recommended to receive yellow fever vaccine Note: Yellow fever is contraindicated in people who are severely immunocompromised, with some exceptions. |
Follow guidance for the general population. Note: Yellow fever is usually contraindicated in pregnant people, other than in exceptional circumstances. |
Follow guidance for the general population. | Serological testing is recommended every 10 years for laboratory workers who may be exposed to yellow fever virus. See recommendation: Laboratory workers who may be exposed to yellow fever virus are recommended to receive yellow fever vaccine |
| Zoster (herpes zoster) | Not routinely recommended. | Serological testing before vaccination may be considered if the immunocompromised person’s previous exposure to varicella vaccination or natural infection is unknown. Testing may be useful in determining the type of vaccine required ie varicella or zoster vaccine; eg prior to HSCT. However, the poor sensitivity of the test may limit interpretation.8 | Not routinely recommended. | Not routinely recommended. | Not routinely recommended. |
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Acronyms used: |
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Serological testing following disease exposure for post-exposure prophylaxis and management
Serological testing can be useful to determine the clinical course of action following exposure to an infected individual in specific circumstances. These are listed in the Table. Indications for serological testing following disease exposure to guide post-exposure prophylaxis and management.
Serological testing is usually not required for post-exposure prophylaxis and management for other vaccine-preventable diseases. Providers should always check guidance on public health management from CDNA and state and territory health authorities.
Serological testing can be useful following exposure to the certain diseases. Refer to local public health policies and CDNA Series of National Guidelines.
| Vaccine antigen | Recommendation for serological testing following disease exposure | Link to further information |
|---|---|---|
| Hepatitis B | Testing is recommended if there is a possibility that the individual is not immune (ie unvaccinated, has not completed a full course of hepatitis B vaccination or vaccination is not documented), especially if they do not have prior documented evidence of a protective response (anti-HBs level of ≥10 mIU/mL). | See recommendations for immunisation against hepatitis B for further details |
| Measles | Serological testing may be warranted following exposure to measles infection. Seronegative individuals should receive vaccination with MMR vaccine. | See recommendations for serological testing for public health management of measles. |
| Rabies and other lyssaviruses |
Serological testing is required for some populations to ensure post-exposure management has reached protective levels. Guidance on testing and recommendations for post-exposure management varies based on individual risk, the type of exposure and vaccination history. |
See recommendations for immunisation against rabies and other lyssaviruses for details. |
| Rubella | Serological testing can be considered following exposure to rubella infection if there is no clear documentation of previous vaccination or history of infection. Seronegative individuals should receive vaccination with MMR vaccine. | See recommendations for serological testing for public health management of rubella. |
| Varicella | Serological testing may be considered to guide post-exposure management, especially for immunocompromised people. | See recommendations for serological testing for public health management of varicella. |
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Acronyms used:
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Serological testing during outbreaks of vaccine-preventable disease
During outbreaks of vaccine-preventable disease, serological testing before vaccinating individuals without clear evidence of immunity (a history of natural infection or vaccination) is not recommended because rapid vaccination is usually necessary to halt disease transmission. In these cases, people at risk of disease exposure should receive vaccination without serological testing (unless vaccination is contraindicated). Follow advice from state and territory public health authorities about public health management of disease outbreaks.
Vaccines for which serological testing is not recommended
Serological testing is either unavailable, unreliable or has no clinical utility in determining the need for vaccination or revaccination for the vaccine-preventable diseases listed in Table. Diseases with vaccination recommendations for which serological testing prior to vaccination is not routinely recommended. Individuals who require these vaccines but do not have clear documentation of prior vaccination should receive age-appropriate catch-up vaccination, without prior serological testing (link to catch-up page).
Although serological testing for the vaccine antigens below is not recommended to inform decisions related to vaccination, testing may have utility for other clinical scenarios, for example in diagnosing immunocompromising conditions. Testing for these purposes should be done under guidance of an immunology specialist.
| Vaccine antigen | Rationale for serological testing being not routinely recommended |
|---|---|
| Cholera | There is no reliable commercial serological test available, and the correlate of protection is unclear |
| COVID-19 | The decision to vaccinate is not influenced by serological testing results (vaccination recommendations are based on risk and timing of previous doses), assays are poorly standardised and a correlate of protection has not been well characterised. |
| Diphtheria | The decision to vaccinate is not influenced by serological testing results (the exception is laboratory workers who may be exposed to toxigenic Corynebacterium diphtheriae in their jobs) |
| Haemophilus influenzae B (Hib) | The decision to vaccinate is not influenced by serological testing results |
| Human papillomavirus (HPV) | There is no reliable commercial serological test available, and the correlate of protection is unclear |
| Influenza | Seasonal influenza vaccination should be given annually, regardless of previous vaccination or serological status |
| Japanese encephalitis | There is no reliable commercial serological test available |
| Meningococcal disease | There is no reliable commercial serological test available, and the correlate of protection is unclear |
| Mpox | There is no reliable commercial serological test available, and the correlate of protection is unclear |
| Pertussis | There is no reliable commercial serological test available, and the correlate of protection is unclear |
| Pneumococcal disease | There is no reliable commercial serological test available, and the correlate of protection is unclear |
| Polio | The decision to vaccinate is not influenced by serological testing results |
| Respiratory Syncytial Virus (RSV) | There is no reliable commercial serological test available, and the correlate of protection is unclear |
| Rotavirus | There is no reliable commercial serological test available, and the correlate of protection is unclear |
| Tetanus | The decision to vaccinate is not influenced by serological testing results |
| Tuberculosis (BCG vaccine) | There is no reliable commercial serological test available |
| Typhoid | There is no reliable commercial serological test available, and the correlate of protection is unclear |
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Acronyms used:
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References
- Orenstein WA, Offit PA, Edwards KM, Plotkin SA, editors. Plotkin's vaccines. 8th ed. Philadelphia, PA: Elsevier; 2023.
- Rubin LG, Levin MJ, Ljungman P, et al. 2013 IDSA clinical practice guideline for vaccination of the immunocompromised host. Clinical Infectious Diseases 2014;58:309-18.
- Siegrist CA, Eberhardt CS. Vaccine immunology. In: Orenstein WA, Offit PA, Edwards KM, Plotkin SA, eds. Plotkin's vaccines. 8th ed. Philadelphia, PA: Elsevier; 2023.
- Ljungman P. Vaccination of Immunocompromised Hosts. In: Orenstein WA, Offit PA, Edwards KM, Plotkin SA, eds. Plotkin's vaccines. 8th ed. Philadelphia, PA: Elsevier; 2023.
- Geretti AM, Brook G, Cameron C, et al. British HIV Association Guidelines on the Use of Vaccines in HIV-Positive Adults 2015. HIV Medicine 2016;17 Suppl 3:s2-s81.
- Cordonnier C, Einarsdottir S, Cesaro S, et al. Vaccination of haemopoietic stem cell transplant recipients: guidelines of the 2017 European Conference on Infections in Leukaemia (ECIL 7). The Lancet Infectious Diseases 2019;19:e200-12.
- Bonanni P, Grazzini M, Niccolai G, et al. Recommended vaccinations for asplenic and hyposplenic adult patients. Human Vaccines and Immunotherapeutics 2017;13:359-68.
- Breuer J, Schmid DS, Gershon AA. Use and limitations of varicella-zoster virus-specific serological testing to evaluate breakthrough disease in vaccinees and to screen for susceptibility to varicella. Journal of Infectious Diseases 2008;197 Suppl 2:S147-51.
Page history
New chapter on recommendations to assess evidence of immunity against vaccine-preventable diseases and inform decisions about vaccination. Includes the following sections:
- Information and general guidance on the use of serological testing to assess evidence of immunity
- Guidance on acceptable evidence of immunity for all vaccine-preventable diseases.
- Information to reflect guidance where serological testing is recommended or may be considered for specific vaccines
- Information to reflect guidance where serological testing may be useful to determine the clinical course of action following exposure to an individual infected with a vaccine-preventable disease
- Information to reflect guidance on where serological testing is not useful in assessing immunity or the need for vaccination
New chapter on recommendations to assess evidence of immunity against vaccine-preventable diseases and inform decisions about vaccination. Includes the following sections:
- Information and general guidance on the use of serological testing to assess evidence of immunity
- Guidance on acceptable evidence of immunity for all vaccine-preventable diseases.
- Information to reflect guidance where serological testing is recommended or may be considered for specific vaccines
- Information to reflect guidance where serological testing may be useful to determine the clinical course of action following exposure to an individual infected with a vaccine-preventable disease
- Information to reflect guidance on where serological testing is not useful in assessing immunity or the need for vaccination