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 KK Aggarwal, Former President, Indian Medical Association. The doctor has replied to queries about the rising cases of COVID-19, the side effects of the COVID-19 vaccine and the proper way to administer the vaccine.

Why is the number of Covid cases increasing so rapidly? Is it because of new mutants?

It is primarily because people are not following Covid appropriate behaviour. It is important to wear a mask properly, maintain 6 feet distance, avoid crowded places, wash hands regularly if we want to prevent the spread of the virus. Covid-19 spreads through the aerosols of an infected person, and it spreads fasts.

However, new mutants can also increase the rate and severity of infection. In both situations, it is important to prevent the spread of the infection by following Covid appropriate behaviour and taking the vaccine when your turn comes.

Why has the duration between the first and the second dose of Covishield been increased? Why has the same not been done for Covaxin?

On the recommendation of the National Technical Advisory Group on Immunisation (NTAGI) and National Expert Group on Vaccine Administration for Covid-19 (NEGVAC), the Health Ministry has increased the duration between the first and the second dose of Covishield from 4-6 weeks to 4-8 weeks.

This recommendation has been made in view of recent scientific evidence, which shows that extending the duration between the two vaccine doses improves its efficacy. A study published in The Lancet (Lancet. 2021 Mar 6;397(10277):881-891) has shown that a longer interval provides better protection after the second dose without affecting the protection in the period before the second dose is administered. The efficacy was 81·3% in individuals who were given the two doses of the vaccine ≥12 weeks apart as compared to those who were given the two doses of the vaccine in a gap of less than 6 weeks, in whom the efficacy is 55·1%.

The second dose of Covaxin can also be given up to 6 weeks. As per the Frequently Asked Questions on Co-WIN (dated 22.3.21) released by the MOHFW and posted on its website, “It is recommended that the 2nd dose of COVAXIN should be administered in the interval of 4 to 6 weeks from the date of 1st dose administration.”

If someone has very strong side effects, does it mean that their immune system against coronavirus is stronger than others? If not, why?

If a person has developed side effects to the vaccine, this does mean that their immune system against coronavirus is stronger than others. It indicates that the vaccine is more reactogenic in some individuals than others. Some degree of reactogenicity is expected after the vaccine and manifests as pain, redness, swelling at the injection site, fever, myalgia, or headache.

If someone has severe side effects after the first dose, does it mean that the effects after the second dose will be similar as well?

No. The second dose may cause no or more severe side effects compared to after the first dose. The side effects are a result of the response of the body’s immune system to the vaccine. The first dose of the vaccine primes the immune system to react to the foreign (vaccine) agent, while the second dose acts as a booster and generates a stronger immune response.

Now that the vaccination process has been opened for those above 45 years old, what will be the next age group to be included in the process?

The next age group to be included will be individuals between 18 and 45 years of age. India is facing a second wave of coronavirus infections. More people will need to take the vaccine if we want to break the chain of transmission. Vaccine wastage will also reduce if there are more takers for the vaccine.

Can the two vaccines be mixed matched? If a person takes the first dose of Covishield, can the second dose be that of Covaxin or vice versa?

No. It is recommended that both doses of vaccine should be taken for realising the full benefit of vaccination. But, both doses must be of the same vaccine type. Two different types of vaccines cannot be mixed.

However, a trial has been launched in the UK to examine whether different vaccines can be safely used interchangeably for the first and second dose. The 13-month study will compare different combinations of the Oxford-AstraZeneca vaccine and Pfizer-BioNTech vaccine.

If a person takes covishield/covaxin’s first dose from one centre, but cannot get the second dose of the same vaccine from the same centre, what should he/she do?

You can go to a vaccination centre administering the same vaccine as the first dose.

Disclaimer: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 address your concerns through this column.