Catalogue of Antibody Tests at Clari Health

Test	What does it measure?	Price
Hepatitis A Immunity Test	Measures IgG and IgM antibodies specific to Hepatitis A	$60
Hepatitis B Immunity Test	Measures IgG and IgM antibodies specific to Hepatitis B	$50
Varicella Zoster Immunity Test	Measures IgG antibodies to determine if an individual has been vaccinated or infected previously	$80
Tetanus Antitoxoid Immunity test	Measures antibodies to determine if an individual has immunity to tetanus after being vaccinated	$25
Measles, Mumps and Rubella Immunity Test	Measures IgG and IgM antibody levels to determine level of immunity against measles, mumps or rubella from previous vaccination	$30

What are vaccine antibody tests?

Vaccine antibody tests help to determine the level of immunity an individual has against a disease-causing virus, bacteria, toxin or microscopic body. They also pick up whether the individual has been infected in the past or is currently harbouring an infection.

The test usually involves collecting a sample of the individual’s blood and testing either for the absence or presence of a specific antibody or the amount of antibodies that are present. These antibodies are immunoglobulin proteins that are a part of the immune system and which serve as a line of defence against virus, bacteria, toxins or other microscopic bodies that invade your body.  

Which antibodies are commonly tested for?

There are five different types of antibodies (immunoglobulin proteins) – IgM, IgG, IgE, IgA and IgD). For simplicity’s sake, we will focus only on IgM and IgG. When a foreign micro-organism such as a virus or bacteria first enters the body, your body’s immune system takes about 2 weeks to produce antibodies to ward off the invaders and infection. The antibody that is first produced is the IgM, which is the immune system’s short-term answer to fighting off the infection.

Once the infection has been successfully fought off and a few weeks have passed, IgG antibodies start to be produced in the body. These IgG antibodies are the long-term solution to fighting off infections. Your body thus keeps a small supply of IgM and IgG antibodies so that the next time you are infected with the same micro-organism, it can more quickly and effectively react and produce IgG antibodies to fight off the infection.

This is why measuring IgM and IgG antibody levels in your blood can either reveal a current or recent infection or immunity built from vaccination.

How can you test if the vaccine you received many years ago is still providing you with adequate immunity against a disease?

Vaccines usually contain either a weakened version of a potentially harmful micro-organism such as a bacteria or virus or a protein that resembles the structure of this micro-organism. Thus, when a vaccine is administered to someone, their body reacts similarly to how it would react if that particular micro-organism had entered the body – however, the reaction is lower in intensity.

Upon the administration of a vaccine, IgM antibodies are produced as the initial response and subsequently, IgG antibodies are also produced. This way, the body is prepared to fight off this particular infection in the future without ever having been infected. This short-term as well as long-term protection is called immunity.

If IgM and IgG antibodies are low in the body, it may suggest that the vaccine you received many years ago may no longer be providing you with subsequent immunity to properly and effectively fight off an infection were it to occur. This means that you may be required to get a booster shot of the vaccine so that antibody levels in your blood are given a boost and your body is once again ready to fight off the infection should it occur.

What antibody levels indicate sufficient immunity to a disease?

Different people produce different levels of antibodies in response to immunisations. They also produce antibodies at varying rates. This means that there is no specific number or figure that indicates an optimal immunity to a disease.

This is why antibody testing results usually reflect a range – “greater than” and “lesser than” being the most common indicators. If the antibody level of an individual is greater than the indicated amount, he or she has sufficient immunity to the disease. If the antibody level is lesser than the indicated amount, he or she may need to look into getting re-vaccinated.

Some tests also have qualitative results such as “antibodies present” and “antibodies absent”. Others may simplify the test interpretation process and classify the person tested as “immune” or “non-immune” to a specific infection.

Nevertheless, no matter how the results are presented, at Clari Health, our travel health nurses will provide you with an interpretation of your antibody test results and provide you with the recommended course of action.

When or why should I get my immunity or antibody levels tested?

Routine Vaccines

Most of us would have received a course of immunisations when we were babies or children. These immunisations are usually administered at a certain age, with booster doses following in subsequent years of childhood. For those living in Singapore, these immunisations would have been done following the National Childhood Immunisation Schedule.

What many people are not aware of however, is that some of these vaccines administered in childhood do not necessarily provide you with immunity for a lifetime. While some vaccines, such as the measles, mumps and rubella vaccine, are classified as vaccines that do not need to be re-taken and which do protect you for the rest of your life, some others will require you to have booster shots to maintain immunity.

An example of a vaccine which will have to be re-administered as a booster shot after 10 years is the Tetanus, diphtheria and pertussis (Tdap) combination vaccine. In the case that you are unsure which routine (childhood) vaccines you may need to get updated on, you can do an antibody test and determine the exact boosters that you may need to receive.

Travel Vaccines

Common travel vaccines such as Hepatitis A, Typhoid and Hepatitis B have varying time periods that they will protect you for. The period that they offer you immunity for usually varies from person to person as each person’s immune system functions differently. For example, a Hepatitis A vaccine course may provide Person A with adequate protection for 15 years while it may protect Person B for only 10 years.

If you are going to be travelling to a country which has a risk of transmission of a certain disease and are unsure whether the vaccine you received many years ago is still providing you with optimal protection, you can get an antibody test done. This way, you can make sure that you get a booster shot before your travels in the case that your antibody levels are sub-optimal and you are no longer adequately protected from the infection.