Vaccine-induced seropositivity
Encyclopedia
Vaccine-induced seropositivity or VISP is the phenomenon wherein a person who has received a vaccine
against a disease would thereafter give a positive or reactive test result for having that disease when tested for it, despite not actually having the disease. This happens because many vaccines encourage the body to produce antibodies against a particular disease, and blood tests often determine whether a person has those antibodies, regardless of whether they came from the infection or just a vaccination.
VISP is especially a concern in vaccine trials for HIV vaccine
research because people who give a positive result in an HIV test
, even if that result is because of a vaccine and not because of an infection, may face discrimination because of HIV infection
.
Many HIV tests work not by checking a person's blood for HIV, but rather by determining whether the body's own antibodies against HIV are present in the blood. Most HIV vaccines are designed with the intent to promote the body's own production of antibodies which would combat HIV. Regardless of whether they are effective at stimulating the production of antibodies which fight HIV, they usually do cause the body to produce antibodies which standard HIV tests recognize as the antibodies which an HIV positive person would produce in response to HIV infection.
A person who is HIV negative, and has received an HIV vaccine, and who then tests as positive in an HIV test is said to be positive because of VISP.
or negotiating for a life insurance
policy.
Between 1987 and 2003 the number of persons who received experimental HIV vaccinations was about 10,000, and this number was considered small. The difficulties in determining the difference between antibodies produced by HIV infection and vaccine-induced antibodies were managed by individual vaccine research sites who had special capability to conduct additional laboratory testing on this small pool of vaccine recipients. However, at this time two new studies, the STEP Study
in the USA and the RV 144
study in Thailand, greatly increased the number of people who received HIV vaccinations by another 4600 people. There came to be an increased need to raise awareness of VISP because more people were exhibiting it.
At the 2010 International AIDS conference
presenters talked about the need for community healthcare providers to understand that if their patients have been in an HIV vaccine trial then their patients are likely to give a false positive HIV test result.
Researchers from Africa, Asia, North America, and South America have said that getting local government and media support of the research is essential in addition to creating facilities for distinguishing between HIV positive individuals and individuals exhibiting VISP.
A study done on participants in the HIV Vaccine Trials Network
HIV vaccination studies showed that among 2176 HIV negative participants who received a vaccine, 908 (42%) had VISP. However, the occurrence of VISP varied depending on what kind of vaccine the participants received.
then the most common test for hepatitis B will show them to be positive. The usual course of action in this case is to give the person a panel of tests for HBsAg
, anti-HBc, and anti-HBs (hepatitis B surface antigen, anti-hepatitis B core, and anti-hepatitis B surface). A person who has never been exposed to hepatitis B but has gotten the vaccine will be positive for anti-HBs but negative for the other two tests in the panel. Other combinations of positive and negative in this test can mean other things, such as acute, chronic, or past infection.
Medical literature on VISP for most diseases is not widely available because there is little practical need for doing that research.
Vaccine
A vaccine is a biological preparation that improves immunity to a particular disease. A vaccine typically contains an agent that resembles a disease-causing microorganism, and is often made from weakened or killed forms of the microbe or its toxins...
against a disease would thereafter give a positive or reactive test result for having that disease when tested for it, despite not actually having the disease. This happens because many vaccines encourage the body to produce antibodies against a particular disease, and blood tests often determine whether a person has those antibodies, regardless of whether they came from the infection or just a vaccination.
VISP is especially a concern in vaccine trials for HIV vaccine
HIV vaccine
An HIV vaccine that protects vaccinated individuals from HIV infection is the goal of many HIV research programmes. Currently, there is no effective vaccine against HIV, the virus that causes AIDS...
research because people who give a positive result in an HIV test
HIV test
HIV tests are used to detect the presence of the human immunodeficiency virus , the virus that causes acquired immunodeficiency syndrome , in serum, saliva, or urine. Such tests may detect antibodies, antigens, or RNA.- Terminology :...
, even if that result is because of a vaccine and not because of an infection, may face discrimination because of HIV infection
Discrimination against people with HIV/AIDS
Discrimination against people with HIV/AIDS is when someone is discriminated against, oppressed or otherwise treated unfairly for their real or perceived diagnosis as HIV-positive....
.
Background
In 1987 in America the first HIV vaccine was tested. HIV vaccines have been tested continually worldwide since then, but thus far, no one has developed any vaccine which reduces a person's risk of contracting HIV if exposed to that virus.Many HIV tests work not by checking a person's blood for HIV, but rather by determining whether the body's own antibodies against HIV are present in the blood. Most HIV vaccines are designed with the intent to promote the body's own production of antibodies which would combat HIV. Regardless of whether they are effective at stimulating the production of antibodies which fight HIV, they usually do cause the body to produce antibodies which standard HIV tests recognize as the antibodies which an HIV positive person would produce in response to HIV infection.
A person who is HIV negative, and has received an HIV vaccine, and who then tests as positive in an HIV test is said to be positive because of VISP.
Significance
When an HIV-negative person exhibits VISP and gets an HIV-positive result from a test then that person may have difficulty donating bloodBlood donation
A blood donation occurs when a person voluntarily has blood drawn and used for transfusions or made into medications by a process called fractionation....
or negotiating for a life insurance
Life insurance
Life insurance is a contract between an insurance policy holder and an insurer, where the insurer promises to pay a designated beneficiary a sum of money upon the death of the insured person. Depending on the contract, other events such as terminal illness or critical illness may also trigger...
policy.
Between 1987 and 2003 the number of persons who received experimental HIV vaccinations was about 10,000, and this number was considered small. The difficulties in determining the difference between antibodies produced by HIV infection and vaccine-induced antibodies were managed by individual vaccine research sites who had special capability to conduct additional laboratory testing on this small pool of vaccine recipients. However, at this time two new studies, the STEP Study
STEP Study
The STEP Study or Phambili Trial was a clinical trial which tested the efficacy of an HIV vaccine. Vaccination in the study ended suddenly and before it was scheduled to finish when pre-determined endpoints happened and indicated that the vaccine being tested certainly was not an effective tool...
in the USA and the RV 144
RV 144
RV 144, or the Thai trial, is the name of an HIV vaccine clinical trial combining two vaccines that failed on their own, vaccinating in Thailand over the course of 24 weeks in October 2003 then testing for HIV until July 2006, publicly releasing efficacy findings in September 2009...
study in Thailand, greatly increased the number of people who received HIV vaccinations by another 4600 people. There came to be an increased need to raise awareness of VISP because more people were exhibiting it.
At the 2010 International AIDS conference
XVIII International AIDS Conference, 2010
The XVIII International AIDS Conference was held in Vienna, Austria from July 18–23, 2010.-Conference theme:The theme of the conference was "Knowledge and Commitment for Action." The International AIDS Society selected this theme to emphasize the need for the general community and public and...
presenters talked about the need for community healthcare providers to understand that if their patients have been in an HIV vaccine trial then their patients are likely to give a false positive HIV test result.
HIV VISP in developing countries
HIV vaccine research happens worldwide to ensure that any vaccine which researchers develop could be used for people worldwide. In developing countries with limited access to healthcare, the problems associated with VISP are a special concern.Researchers from Africa, Asia, North America, and South America have said that getting local government and media support of the research is essential in addition to creating facilities for distinguishing between HIV positive individuals and individuals exhibiting VISP.
Likelihood
People who participate in vaccine trials which test HIV vaccines may exhibit VISP for years or for the rest of their lives.A study done on participants in the HIV Vaccine Trials Network
HIV Vaccine Trials Network
The HIV Vaccine Trials Network is a non-profit organization which connects physicians and scientists with activists and community educators for the purpose of conducting clinical trials seeking a safe and effective HIV vaccine. Collaboratively, research professionals and laypeople review...
HIV vaccination studies showed that among 2176 HIV negative participants who received a vaccine, 908 (42%) had VISP. However, the occurrence of VISP varied depending on what kind of vaccine the participants received.
Hepatitis B
When a person gets a hepatitis B vaccineHepatitis B vaccine
Hepatitis B vaccine is a vaccine developed for the prevention of hepatitis B virus infection. The vaccine contains one of the viral envelope proteins, hepatitis B surface antigen . It is produced by yeast cells, into which the genetic code for HBsAg has been inserted...
then the most common test for hepatitis B will show them to be positive. The usual course of action in this case is to give the person a panel of tests for HBsAg
Hbsag
HBsAg is the surface antigen of the Hepatitis-B-Virus . It indicates current Hepatitis B infection.-Structure and function:The capsid of a virus has different surface proteins from the rest of the virus which act as antigens...
, anti-HBc, and anti-HBs (hepatitis B surface antigen, anti-hepatitis B core, and anti-hepatitis B surface). A person who has never been exposed to hepatitis B but has gotten the vaccine will be positive for anti-HBs but negative for the other two tests in the panel. Other combinations of positive and negative in this test can mean other things, such as acute, chronic, or past infection.
Other conditions
VISP is not often a practical concern for other diseases because in most cases good vaccines already exist and most people who have access to healthcare receive them. Also doctors do not routinely test people for recent infections with most diseases as they do for HIV.Medical literature on VISP for most diseases is not widely available because there is little practical need for doing that research.