Based on a Q&A with Dr. Gagandeep Kang, professor of microbiology at the Wellcome Trust Research Laboratory, Division of Gastrointestinal Sciences at the Christian Medical College in Vellore, India, held on May 12, 2021, and co-organized by IAVI and DBT/Wellcome Trust India Alliance.
How does a COVID-19 vaccine work?
Since the development of the smallpox vaccine in 1796, all vaccines have worked in the same way; they essentially mimic infections. Vaccines contain an inactivated version of the virus, a specific part of the virus, or a piece of its genetic material, to trick your body into thinking that it is infected in order to induce an immune response to protect you,without actually making you sick.
While COVID-19 vaccines do not prevent you from getting infected, they can reduce the severity of the disease.
How many different strains of the virus are currently active in India?
SARS-CoV-2 is an RNA virus. RNA viruses can mutate very quickly, and sometimes this makes them more infectious. For this reason, it is very important to track variants and their impact on both individuals and populations.
We are not sure about the exact number of variants in India because we have not done adequate genomic sequencing to track them, but the B.1.617 variant, or the Delta variant, is recognized as being largely responsible for the situation in India today1. We also have the B.1.1.7 variant, or Alpha variant, first recognized in the UK; B.1.351, or Beta variant, first recognized in South Africa; and, P1, or the Gamma variant, first recognized in Brazil2.
What are the different kinds of vaccines available in India? What is their proven efficacy?
There are two vaccines currently in India; one is Covishield, which has been developed by Oxford-AstraZeneca and manufactured by Serum Institute in India. The other is Covaxin, which has been developed by Bharat Biotech, in collaboration with the Indian Council of Medical Research (ICMR) - National Institute of Virology (NIV).
Covaxin is an inactivated vaccine. Inactivated vaccines contain viruses whose genetic material has been chemically treated so they cannot replicate but can still trigger an immune response.
Covishield is an adenovirus vectored vaccine. Adenoviruses are a family of common viruses which usually cause flu or cold-like symptoms. Adenovirus vectored vaccines are developed using a modified and harmless adenovirus as a Trojan horse to deliver the genetic instructions of the SARS-CoV-2 virus. These genetic instructions teach your body to produce spike proteins like those that adorn the outer shell of the virus, thereby creating an immune response.
Sputnik V, developed by the Russian Direct Investment Fund and Gamaleya Research Institute of Epidemiology and Microbiology, will also be available in India soon, and will be distributed by Dr Reddy’s. Over a period of time, the vaccine is also going to be manufactured in India. Like Covishield, Sputnik is an adenovirus vectored vaccine.
There are more vaccines on the way, but it will take another 3-4 months before we can see them at our vaccination centers.
We have more data on Covishield, because this vaccine is also being used outside of India. The vaccine has a clinical efficacy of 63% against symptomatic SARS-CoV-2infection3. Against variants of concern, the vaccine was seen to be 66% effective against the B.1.1.7 variant, and 60% effective against the B.1.617 variant4.
Interim data from Phase III trials of Covaxin5 shows that the vaccine is 78% effective against infection, and 100% effective against progression to severe disease. However, there is no data available regarding efficacy against different variants of the virus.
How much time does it take for vaccines to produce an adequate immune response?
As per the Ministry of Health and Family Welfare, Government of India, an adequate immune response from both Covaxin and Covishield takes 2-3 weeks after completing the entire vaccination schedule, i.e. after the second dose6.
What is the optimal gap between two doses? How long does this protection last? Do these vaccines work for all variants?
The longer the gap, the more robust the immune response.
The National Technical Advisory Group on Immunisation (NTAGI) recently recommended increasing the gap between two doses of Covishield to 12-16 weeks7. The second dose of Covaxin should be taken 4-6 weeks after the first.
Researchers are not sure how long the protection provided by vaccines last; SARS-CoV-2 is a new type of virus, and because COVID-19 vaccines have been developed very quickly, there are still studies being done on how long protection lasts. However, we do have research from other vaccines, and that is being used to understand the potential duration of protection. Now that COVID-19 vaccines are in wider use, we are also getting more answers to previously unanswered questions.
We do not have data on how many variants exist at the moment, nor are there enough people vaccinated in order to assess if vaccines work against these variants.
Can people with diabetes, HIV, TB, autoimmune disorders, renal insufficiency, pulmonary diseases, and other comorbidities take vaccines? Are there any precautions that need to be taken?
It is, in fact, more important for people with diabetes and other illnesses to take the vaccine, because these groups are vulnerable to developing a severe illness if they doget COVID-19, and vaccines are the most effective way to prevent that from happening.The only time you should not be taking the vaccine is if you are allergic to any component of it. If you had a bad, potentially life-threatening allergic reaction (called anaphylaxis) to your first dose, you should not take your second dose.
Also, if you are immunocompromised, you must continue to be careful even after vaccination. This is because the protection you receive from the vaccine may not be as good as somebody who does not have these illnesses.
Can pregnant and breastfeeding women take the vaccine?
In April 2021, the Federation of Obstetric and Gynaecological Societies of India (FOGSI) released a statement which said the “very real benefits of vaccinating pregnant and lactating women seem to far outweigh any theoretical and remote risks of vaccination.Lactating women should also be considered as COVID vaccine candidates as there are no known adverse effects on the neonate who is breastfeeding. In fact, there is a passage of protective antibodies to the child.”8
FOGSI also noted that, as compared to non-pregnant women and pregnant women who are not infected with COVID-19, pregnant women who are infected with COVID-19 are more likely to need hospitalization and critical care.
We also have data from the first study done on pregnant and lactating women in the United States, which concluded that the mRNA vaccination generates an equally robust immune response in pregnant and lactating women, as it does in the general population9. The study also saw evidence of protective antibodies in umbilical cord blood and breast milk, implying that the vaccine provides protection to both the fetus and newborn.
While the safety of the vaccines in pregnant and breastfeeding women is being investigated, data published from one study showed no increase in maternal side effects with vaccine administration in pregnancy, as compared to non-pregnant women. The study also found that the women who delivered after receiving the vaccine in pregnancy did not show any increased risk of the above-mentioned events10.
It is important to note, however, that there is no data available on the immunization of pregnant and breastfeeding women after getting either Covishield or Covaxin. While national and international professional bodies have taken a universally positive stance on vaccination in these populations, this lack of data has been flagged. These groups are encouraged to make an informed choice in the matter; speak to a doctor if you have any concerns.
What precautions should be taken at the vaccination center, given the challenges we are seeing with physical distancing?
The limit of 100 vaccines per vaccination session, set by the Government of India, was to address crowding at centers. However, people are testing positive after visiting vaccination centers and receiving their first dose. It is, therefore, recommended to maintain social distancing at the vaccination center as much as possible, wear a double mask, and carry a bottle of hand sanitizer with you.
When can I get my second dose if I was infected between doses?
The World Health Organization (WHO) recommends that, if you are infected after the first dose, you can wait for 6 months to get your second dose11.
There is, currently, a shortage of vaccines in the country. If I have received one dose of one vaccine, but it is not available now, can I take the second dose of a different vaccine?
The current recommendation is that you should take both doses of the same vaccine.
The National Technical Advisory Group on Immunization (NTAGI) has said that the country may soon start testing the feasibility of a regimen that mixes two different doses of COVID-19 vaccines, to see if it helps boost the immune response12.
The shortage of vaccines is worrying at the moment; however, we will have more vaccines available by the end of 2021. It is important to get everyone vaccinated.
Post vaccination, what are some of things people need to be careful of? What are the chances of transmitting the virus?
Vaccines do not contain live viruses; you cannot get COVID-19 from the vaccine, nor can you transmit it as a result of vaccination. However, if you are infected, then you can always transmit the virus to others.
There is a proportion of people who have been infected, even after vaccination. Vaccines are not intended to prevent infection; they are intended to prevent disease.
It has been predicted that children will be more impacted in the third wave of the pandemic. Is this true?
Children were always involved in the first and second wave, however 90% of cases have been mild or asymptomatic so far13. The prediction that children will be more affected in the third wave is largely on the presumption that they are more likely to be unvaccinated compared to adults.
The United States has already begun vaccinating children between the ages of 12-18 years, and India will have to do the same soon14.
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