How Quickly After the Second Dose Of COVID-19 Vaccine Do You Develop Immunity?

A year after the Coronavirus pandemic wrecked our collective lives, our society has been grappling with fear and insecurity. As a result, we have seen misinformation spread like wildfire, and many resorting to bizarre and incorrect methods of dealing with the virus. With this column, which will be published every Sunday, we aim to address any health or vaccine-related question our readers might have about the coronavirus pandemic.

In this week’s column, the queries have been answered by Dr Rakesh Aggarwal, Director Jawaharlal Institute of Postgraduate Medical Education and Research (JIPMER) Puducherry, India. In this column, Dr Aggarwal answers questions about vaccine efficacy, and the effect of the vaccine on hormones, and thyroid gland.

After receiving the two doses of the vaccine, is there a way to check that my body has developed COVID 19 antibodies?

Yes. The vaccine leads to the development of antibodies and cellular immunity against the SARS-CoV-2, the virus which causes Covid-19. Thus, one can test the blood of the vaccinated person for antibodies to this virus. However, this test is not recommended as a routine since antibodies appear in most of the immunized persons anyway, and the test is tedious. Also, even those few who do not develop detectable antibodies do achieve some protection against Covid-19 through the development of cellular immune responses, which are more difficult to measure.

How soon after the second dose of vaccine does a person develop immunity?

A fair degree of protection appears by around 15 days after the first dose. However, this protection may not be long-lasting. The antibody level, and hence the degree of immunity, increases several-fold after the second dose and reaches close to a peak at around 15 days after the second dose.

Will the effect of the vaccine wear off? How do we know when the vaccine is no longer effective?

Among vaccines for other diseases, the effect of some declines over time, but others give life-long immunity. For any vaccine, the duration for which its protective effect lasts can be known only by following the vaccinated persons over time. Covid-19 vaccines have been around for too little for us to reliably know the duration of protection conferred by them.

Can COVID 19 vaccine aggravate autoimmune diseases like psoriasis and lupus?

No. The vaccine is designed to induce immunity specifically against the proteins of SARS-CoV-2, the virus that causes Covid-19, and not against other proteins. Thus, it is not likely to aggravate autoimmune diseases. Covid-19 vaccines have already been administered to several million people worldwide and to more than 2 crore persons in India, and no such aggravation has been observed.

If someone who had already had COVID 19 also takes the vaccine, what will happen to him/her?

Administration of Covid-19 vaccine to a person who has already had Covid-19 is entirely safe. In fact, such persons should also take Covid-19 vaccine just like other people. This is because a proportion of persons who have had Covid-19 disease or infection have only low level of antibodies to the virus. Giving them vaccines leads to more of them having protective antibodies and a larger amount of antibodies in their blood, reducing further the risk of a second attack of Covid-19.

Does the COVID-19 impact the thyroid gland or our hormones balance in any way?

As of now, Covid-19 is not known to interfere in a significant manner with the functioning of the thyroid gland or alter the hormone manner much. The effect, if any, appears to be minor and not of much clinical relevance.

Do you have questions about Coronavirus? Or the vaccines? Send us your questions: Tweet with #AskADoctor. Every week, we will have a public health expert to address your concerns through this column.

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