For many students and new healthcare workers submitting their documentation for vaccine requirements, this is the first time they begin to think critically about how vaccines work and why immunity needs to be documented. In an ideal situation, these requirements are firmly rooted in science and vaccine effectiveness, and the requirements make sense to the individual. However, it is not uncommon for students and new employees to raise questions about the requirements. Clear, accurate reasoning helps people build a real understanding of how we use vaccines in practice.
At their core, immunity requirements exist to protect the individual. Clinical training and patient care increase the chance of encountering certain pathogens, sometimes unexpectedly. A healthcare worker might stumble into a case of measles or be exposed to bloodborne pathogens without warning. Requirements should, therefore, be straightforward and designed to ensure true protection.
Additionally, vaccinating healthcare providers reduces the chance that they could unknowingly pass an infection to a patient or co-workers. Workforces that are fully vaccinated for infections, such as influenza, also have lower rates of absenteeism, which is safer for patient care and more cost effective for the healthcare system.
We sometimes get questions at the Vaccine Education Center related to requirements for students and healthcare workers, so this month we wanted to take a deeper dive into some of these questions and the science behind them.
Measles serology
I’m a nursing student, and prior to my clinical rotations, I was asked to get bloodwork to confirm my immunity to measles. This was confusing to me as I am 22 years old and have documentation of two doses of measles vaccine as a child. Why are they asking me to do this?
You’re not alone in being confused.
Let’s take a step back. Blood samples can be used to measure the amount of antibodies circulating in a person’s blood. For determining measles immunity in a situation such as this, the test will measure IgG antibodies. If someone has at least 16.5 International Units per milliliter (IU/ml), they are considered immune. A negative result is less than 13.4 IU/ml. However, measles IgG tests can be falsely negative because antibody levels decline naturally over time even though immunologic memory remains strong.
For this reason, a 22-year-old with written proof of two appropriately timed MMR doses is not recommended to have a blood test to check their immune status. This recommendation has been consistent for years: Someone who got two doses of measles-containing vaccine after their first birthday with at least 28 days between the doses should be considered to have lifelong immunity to measles. The data behind this recommendation are compelling. Two doses of MMR vaccine protect about 97of 100 people from measles, and although IgG antibodies in the blood may not be detectable, immunity doesn’t wane because of strong immunologic memory.
So, why do some programs still ask healthcare-based students to get a blood test even when they have their vaccination records? The reasons are typically unrelated to the science behind vaccine effectiveness. Some institutions simply haven’t updated old policies. Others may incorrectly believe that lab results provide better or additional proof of immunity that could increase patient and staff protection or that the policy provides a legal safeguard if questions arise related to exposures, such as in worker’s compensation claims.
Tdap/Td requirements
I run a student health clinic for a large university and had a student come to request a copy of their vaccine records to begin their clinical rotations. I noticed their last Tdap was 11 years ago and recommended another dose since Tdap/Td is recommended for adults every 10 years. However, the student refused because the health system doesn’t require documentation for this vaccine. Why is there a discrepancy?
Healthcare worker vaccine requirements focus on risks associated with exposures that are more likely because of the person’s clinical work. As such, in a clinical setting the concern would be exposure to pertussis since tetanus is not spread from person to person, and diphtheria is unlikely in the U.S.
Unfortunately, the challenge is that the pertussis vaccine only provides protection for about four to five years. In the event of a clinical exposure, a healthcare worker vaccinated within the last few years would likely still need post-exposure prophylaxis. Likewise, previous pertussis vaccination doesn’t decrease the spread of this infection in healthcare settings because someone who has been vaccinated can still experience mild or asymptomatic illness during which time they can spread the bacteria to others. Because of these constraints, some healthcare systems have removed the requirement for recent receipt of pertussis-containing vaccines.
Universities, however, may reasonably recommend a different policy. Because students live in dorms or shared living spaces where the bacteria can easily spread during outbreaks and because immunity offers protection against pertussis for four to five years, a dose of Tdap at the beginning of a student’s tenure on campus can offer protection from pertussis during the two- to four-year period when they will be living in crowded housing.
In some cases, universities confirm that students have received a dose of Td in the past 10 years, without mention of the pertussis component. In this instance, the policy is more likely focused on ensuring that individuals have received the recommended vaccines for their age, particularly because sometimes vaccines are missed when teens and healthy young adults have fewer interactions with the medical system.
Because the considerations made by universities and healthcare systems can differ, students or staff may have questions. By explaining the underlying reasoning, you can help them realize the value of and nuance associated with vaccination considerations and the utility of divergent recommendations for different populations and situations.
Titers as evidence of immunity (MMR and varicella)
I have a student who only received one dose of MMR and one dose of varicella. She had an allergic reaction after her 1-year-old vaccines, and they were never able to figure out which vaccine caused the reaction. Do her titers suffice for evidence of immunity even if she only got one dose of each vaccine?
The short answer is yes, but let’s take a deeper dive:
- As described in a previous question, the measles IgG test may provide false negatives, meaning someone is immune, but they don’t have measurable levels of IgG antibodies in their bloodstream. It is for this reason, that someone with documentation of two doses of MMR is not recommended to get a blood test to confirm immunity.
- However, if a person only had one dose of the vaccine, the situation is a bit different. As a reminder, the second dose of MMR likely enhances a person’s immunologic memory for measles and mumps. But the main reason for the second dose is to catch the people who did not develop measles immunity after the first dose. So, in a person with only one documented dose of MMR, the blood test can help us confirm that the individual was not one of the small numbers of non-responders to measles. As such, if the person’s blood test comes back positive, they are considered immune even with only one prior dose.
- Mumps serology can be used to document immunity and can be used to begin employment, but it does not necessarily predict long-term protection against mumps disease because of waning immunity. In the event of an outbreak, public health authorities may communicate the need for an additional dose of mumps-containing vaccine.
- As for rubella, a single dose of rubella-containing vaccine is sufficient for protection.
- In the case of varicella (chickenpox), the situation related to the recommendation of a second dose is similar in that the additional dose increases protection among those who did not develop adequate immunity after the first dose, but the second dose also increases individual immunity, resulting in fewer cases of breakthrough infections.
In terms of allergic responses to varicella vaccine, anaphylaxis following receipt of the vaccine or to a vaccine ingredient, such as gelatin, is a contraindication. It may be worth understanding more about the student’s vaccine reaction at 1 year of age as it may not be considered a contraindication.
A few other points about accepted evidence of immunity for healthcare workers related to these vaccines are worth noting:
- Measles immunity for individuals born before 1957: People born before 1957 are considered to be immune to measles because the virus is highly contagious and there was no vaccine at that time. However, healthcare workers should still be offered vaccine, and if there is an outbreak, they should have their immunity confirmed either by laboratory testing or documentation of vaccination.
- Chickenpox immunity for individuals born before 1980: While the majority of the public born before 1980 is immune to chickenpox, this criteria should not be considered as evidence of immunity for healthcare workers because of the chance for spreading this infection to high-risk patients in the healthcare setting.
- Documentation of chickenpox infection: Provider documentation of chickenpox or shingles is considered sufficient evidence of immunity against varicella as studies have consistently shown this to be a reliable proxy. Notably, self-reports are no longer acceptable because of lack of familiarity with this infection. Similarly, in the current vaccine era when clinicians less frequently diagnose chickenpox and milder or atypical rashes are more common, providers can also occasionally misdiagnose the disease. As such, some occupational health programs are now asking for blood tests to better ensure immunity.
Hepatitis B immunity
Why are both hepatitis B vaccination and titers required for healthcare workers when this differs from all the other vaccines? This doesn’t seem cost effective.
Hepatitis B is spread through blood. Because of the large quantities of virus in blood, it can spread through exposure to miniscule quantities of blood — even too miniscule to be seen. We also know that many people with chronic hepatitis B infections remain undiagnosed. Finally, people who work in healthcare are likely to come into contact with blood, including in situations where accidental or unprotected exposures can occur — especially early in training. For these reasons, healthcare worker requirements around hepatitis B vaccination are among the most stringent.
In fact, the Occupational Safety and Health Administration (OSHA), the federal agency that sets and enforces workplace safety standards, sets standards around bloodborne pathogens, including hepatitis B protections for healthcare workers. OSHA’s standard requires employers to offer hepatitis B vaccination to workers with potential for exposure as well as to provide post-vaccination antibody testing when indicated. Employees can decline the vaccine, but they must sign a formal declination acknowledging the risk they are taking by remaining unprotected.
When it comes to hepatitis B vaccine, we know that completing the two- or three-dose series doesn’t guarantee adequate long-term antibody levels. About 5 to 10 of every 100 people don’t develop a robust response to the hepatitis B vaccine. The only way to know who didn’t respond is by checking antibody levels in a person’s blood. After vaccination, people with at least 10 milli-international units per milliliter (mIU/mL) are considered to have lifelong protection. Those without these levels of antibodies need some follow-up steps. For more on the considerations and communication related to this, check out the article, “News & Views: Communicating with Patients about Hepatitis B Surface Antibodies.”
Wrap-up
When students and new employees have questions about vaccine recommendations or requirements, it’s important to take the opportunity to explain the scientific logic behind them. These conversations not only present the perfect moment to validate the practice of asking questions about vaccines but also offer an opportunity to provide clear, science-based answers that can help them feel more comfortable and informed when making vaccine decisions. Likewise, when a requirement doesn’t fully align with science, try to be transparent and provide the nonclinical forces shaping the policy so that the individual can understand the “whys” of the situation. As these questions are coming from current or future healthcare providers, these conversations position individuals to be better able to adequately respond to questions they may receive from patients and families in the future.
Resources
- Healthcare Personnel Vaccination Recommendations
- OSHA FactSheet
- Immunization of Health-Care Personnel: Recommendations of the Advisory Committee on Immunization Practices (ACIP)
Contributed by: Lori Handy, MD, MSCE , Charlotte A. Moser, MS, Paul A. Offit, MD
For many students and new healthcare workers submitting their documentation for vaccine requirements, this is the first time they begin to think critically about how vaccines work and why immunity needs to be documented. In an ideal situation, these requirements are firmly rooted in science and vaccine effectiveness, and the requirements make sense to the individual. However, it is not uncommon for students and new employees to raise questions about the requirements. Clear, accurate reasoning helps people build a real understanding of how we use vaccines in practice.
At their core, immunity requirements exist to protect the individual. Clinical training and patient care increase the chance of encountering certain pathogens, sometimes unexpectedly. A healthcare worker might stumble into a case of measles or be exposed to bloodborne pathogens without warning. Requirements should, therefore, be straightforward and designed to ensure true protection.
Additionally, vaccinating healthcare providers reduces the chance that they could unknowingly pass an infection to a patient or co-workers. Workforces that are fully vaccinated for infections, such as influenza, also have lower rates of absenteeism, which is safer for patient care and more cost effective for the healthcare system.
We sometimes get questions at the Vaccine Education Center related to requirements for students and healthcare workers, so this month we wanted to take a deeper dive into some of these questions and the science behind them.
Measles serology
I’m a nursing student, and prior to my clinical rotations, I was asked to get bloodwork to confirm my immunity to measles. This was confusing to me as I am 22 years old and have documentation of two doses of measles vaccine as a child. Why are they asking me to do this?
You’re not alone in being confused.
Let’s take a step back. Blood samples can be used to measure the amount of antibodies circulating in a person’s blood. For determining measles immunity in a situation such as this, the test will measure IgG antibodies. If someone has at least 16.5 International Units per milliliter (IU/ml), they are considered immune. A negative result is less than 13.4 IU/ml. However, measles IgG tests can be falsely negative because antibody levels decline naturally over time even though immunologic memory remains strong.
For this reason, a 22-year-old with written proof of two appropriately timed MMR doses is not recommended to have a blood test to check their immune status. This recommendation has been consistent for years: Someone who got two doses of measles-containing vaccine after their first birthday with at least 28 days between the doses should be considered to have lifelong immunity to measles. The data behind this recommendation are compelling. Two doses of MMR vaccine protect about 97of 100 people from measles, and although IgG antibodies in the blood may not be detectable, immunity doesn’t wane because of strong immunologic memory.
So, why do some programs still ask healthcare-based students to get a blood test even when they have their vaccination records? The reasons are typically unrelated to the science behind vaccine effectiveness. Some institutions simply haven’t updated old policies. Others may incorrectly believe that lab results provide better or additional proof of immunity that could increase patient and staff protection or that the policy provides a legal safeguard if questions arise related to exposures, such as in worker’s compensation claims.
Tdap/Td requirements
I run a student health clinic for a large university and had a student come to request a copy of their vaccine records to begin their clinical rotations. I noticed their last Tdap was 11 years ago and recommended another dose since Tdap/Td is recommended for adults every 10 years. However, the student refused because the health system doesn’t require documentation for this vaccine. Why is there a discrepancy?
Healthcare worker vaccine requirements focus on risks associated with exposures that are more likely because of the person’s clinical work. As such, in a clinical setting the concern would be exposure to pertussis since tetanus is not spread from person to person, and diphtheria is unlikely in the U.S.
Unfortunately, the challenge is that the pertussis vaccine only provides protection for about four to five years. In the event of a clinical exposure, a healthcare worker vaccinated within the last few years would likely still need post-exposure prophylaxis. Likewise, previous pertussis vaccination doesn’t decrease the spread of this infection in healthcare settings because someone who has been vaccinated can still experience mild or asymptomatic illness during which time they can spread the bacteria to others. Because of these constraints, some healthcare systems have removed the requirement for recent receipt of pertussis-containing vaccines.
Universities, however, may reasonably recommend a different policy. Because students live in dorms or shared living spaces where the bacteria can easily spread during outbreaks and because immunity offers protection against pertussis for four to five years, a dose of Tdap at the beginning of a student’s tenure on campus can offer protection from pertussis during the two- to four-year period when they will be living in crowded housing.
In some cases, universities confirm that students have received a dose of Td in the past 10 years, without mention of the pertussis component. In this instance, the policy is more likely focused on ensuring that individuals have received the recommended vaccines for their age, particularly because sometimes vaccines are missed when teens and healthy young adults have fewer interactions with the medical system.
Because the considerations made by universities and healthcare systems can differ, students or staff may have questions. By explaining the underlying reasoning, you can help them realize the value of and nuance associated with vaccination considerations and the utility of divergent recommendations for different populations and situations.
Titers as evidence of immunity (MMR and varicella)
I have a student who only received one dose of MMR and one dose of varicella. She had an allergic reaction after her 1-year-old vaccines, and they were never able to figure out which vaccine caused the reaction. Do her titers suffice for evidence of immunity even if she only got one dose of each vaccine?
The short answer is yes, but let’s take a deeper dive:
- As described in a previous question, the measles IgG test may provide false negatives, meaning someone is immune, but they don’t have measurable levels of IgG antibodies in their bloodstream. It is for this reason, that someone with documentation of two doses of MMR is not recommended to get a blood test to confirm immunity.
- However, if a person only had one dose of the vaccine, the situation is a bit different. As a reminder, the second dose of MMR likely enhances a person’s immunologic memory for measles and mumps. But the main reason for the second dose is to catch the people who did not develop measles immunity after the first dose. So, in a person with only one documented dose of MMR, the blood test can help us confirm that the individual was not one of the small numbers of non-responders to measles. As such, if the person’s blood test comes back positive, they are considered immune even with only one prior dose.
- Mumps serology can be used to document immunity and can be used to begin employment, but it does not necessarily predict long-term protection against mumps disease because of waning immunity. In the event of an outbreak, public health authorities may communicate the need for an additional dose of mumps-containing vaccine.
- As for rubella, a single dose of rubella-containing vaccine is sufficient for protection.
- In the case of varicella (chickenpox), the situation related to the recommendation of a second dose is similar in that the additional dose increases protection among those who did not develop adequate immunity after the first dose, but the second dose also increases individual immunity, resulting in fewer cases of breakthrough infections.
In terms of allergic responses to varicella vaccine, anaphylaxis following receipt of the vaccine or to a vaccine ingredient, such as gelatin, is a contraindication. It may be worth understanding more about the student’s vaccine reaction at 1 year of age as it may not be considered a contraindication.
A few other points about accepted evidence of immunity for healthcare workers related to these vaccines are worth noting:
- Measles immunity for individuals born before 1957: People born before 1957 are considered to be immune to measles because the virus is highly contagious and there was no vaccine at that time. However, healthcare workers should still be offered vaccine, and if there is an outbreak, they should have their immunity confirmed either by laboratory testing or documentation of vaccination.
- Chickenpox immunity for individuals born before 1980: While the majority of the public born before 1980 is immune to chickenpox, this criteria should not be considered as evidence of immunity for healthcare workers because of the chance for spreading this infection to high-risk patients in the healthcare setting.
- Documentation of chickenpox infection: Provider documentation of chickenpox or shingles is considered sufficient evidence of immunity against varicella as studies have consistently shown this to be a reliable proxy. Notably, self-reports are no longer acceptable because of lack of familiarity with this infection. Similarly, in the current vaccine era when clinicians less frequently diagnose chickenpox and milder or atypical rashes are more common, providers can also occasionally misdiagnose the disease. As such, some occupational health programs are now asking for blood tests to better ensure immunity.
Hepatitis B immunity
Why are both hepatitis B vaccination and titers required for healthcare workers when this differs from all the other vaccines? This doesn’t seem cost effective.
Hepatitis B is spread through blood. Because of the large quantities of virus in blood, it can spread through exposure to miniscule quantities of blood — even too miniscule to be seen. We also know that many people with chronic hepatitis B infections remain undiagnosed. Finally, people who work in healthcare are likely to come into contact with blood, including in situations where accidental or unprotected exposures can occur — especially early in training. For these reasons, healthcare worker requirements around hepatitis B vaccination are among the most stringent.
In fact, the Occupational Safety and Health Administration (OSHA), the federal agency that sets and enforces workplace safety standards, sets standards around bloodborne pathogens, including hepatitis B protections for healthcare workers. OSHA’s standard requires employers to offer hepatitis B vaccination to workers with potential for exposure as well as to provide post-vaccination antibody testing when indicated. Employees can decline the vaccine, but they must sign a formal declination acknowledging the risk they are taking by remaining unprotected.
When it comes to hepatitis B vaccine, we know that completing the two- or three-dose series doesn’t guarantee adequate long-term antibody levels. About 5 to 10 of every 100 people don’t develop a robust response to the hepatitis B vaccine. The only way to know who didn’t respond is by checking antibody levels in a person’s blood. After vaccination, people with at least 10 milli-international units per milliliter (mIU/mL) are considered to have lifelong protection. Those without these levels of antibodies need some follow-up steps. For more on the considerations and communication related to this, check out the article, “News & Views: Communicating with Patients about Hepatitis B Surface Antibodies.”
Wrap-up
When students and new employees have questions about vaccine recommendations or requirements, it’s important to take the opportunity to explain the scientific logic behind them. These conversations not only present the perfect moment to validate the practice of asking questions about vaccines but also offer an opportunity to provide clear, science-based answers that can help them feel more comfortable and informed when making vaccine decisions. Likewise, when a requirement doesn’t fully align with science, try to be transparent and provide the nonclinical forces shaping the policy so that the individual can understand the “whys” of the situation. As these questions are coming from current or future healthcare providers, these conversations position individuals to be better able to adequately respond to questions they may receive from patients and families in the future.
Resources
- Healthcare Personnel Vaccination Recommendations
- OSHA FactSheet
- Immunization of Health-Care Personnel: Recommendations of the Advisory Committee on Immunization Practices (ACIP)
Contributed by: Lori Handy, MD, MSCE , Charlotte A. Moser, MS, Paul A. Offit, MD