Bengaluru: As the second wave of the pandemic rages on in India, a number of people, including those who have either recovered from Covid-19 or have tested positive, are now ready to be vaccinated against the disease.
So, when should a recovered person get vaccinated? What happens when a person catches Covid between two doses of vaccines? What if someone misses their second dose?
ThePrint answers this and some more frequently asked questions regarding vaccination, Covid recovery, and the body’s immune response.
When should I get vaccinated after I have tested positive?
The US’ Centres for Disease Control and Prevention (CDC) recommends that a person get vaccinated immediately after recovery, while the World Health Organization (WHO) states that a person should wait six months as natural antibodies seem to likely persist in the human body until then.
In India, most doctors recommend arbitrary gaps between recovery and vaccination, typically between one and three months.
Waiting to get vaccinated after recovery not only allows others who have remained uninfected to receive their first dose, but also improves immune response, says Dr Gagandeep Kang, immunologist at Christian Medical College, Vellore.
“Getting Covid is like getting a vaccine dose,” said Kang. “We recommend waiting four to eight weeks after recovery before taking the vaccine as you have natural antibodies. Plus, you would still be responding to the infection, so vaccinating at that time would be a waste of the vaccine,” she explains.
Allowing the body to completely recover from the infection and also build up natural immunity before getting a shot to further boost one’s immune response makes more sense, she adds.
What happens if I take the vaccine when I’m positive?
When we get infected, the first antibody a person’s body makes is the IgM antibody. Production of these antibodies start a week into the infection, peaks at three weeks, and declines very quickly afterward.
About three weeks after infection, the IgG antibodies start to get produced, which are less generic and more specific to the pathogen infecting the body. These are the more crucial antibodies to look out for, and they climb in quantity from four to eight weeks after infection. Subsequently, they decline slowly in numbers.
The IgG antibody response is what matters for Covid-19, and the second dose of all vaccines provides a boost to this antibody response.
“We do not currently have any evidence to say whether it is better or worse to get vaccinated when infected, whether in terms of immune response or any safety issue,” says Dr Kang.
However, vaccinating after recovery acts like a booster shot, improving protection.
What if I catch Covid in between two vaccine doses?
For a majority of persons, the disease is likely to be mild or moderate, depending on how many days after vaccination exposure occurred.
If exposure and disease occurs within two to three weeks of receiving the first dose, the vaccine is unlikely to have a major effect and is not expected to modify the course of the infection. However, if a person tests positive after four weeks from their first dose, they are highly likely to only get a mild disease.
Once the body is infected, has the disease and starts producing antibodies, it is once again effectively akin to getting a vaccine.
In principle, follow the same protocol, says Kang. “Wait at least four weeks after recovery before you take the second dose.”
What happens if I delay the second dose? Will I need to repeat the first dose?
Trials have indicated there are optimal timings for a booster shot to achieve a high level of antibodies in the system. For the AstraZeneca-Oxford vaccine Covishield, it is 12 weeks, while for the indigenous Covaxin, a gap of six weeks is recommended.
But missing the second dose is no cause for worry, assures Kang. It simply postpones the boosting of the antibodies and does not result in any loss of protection. Missing the time period allocated does not require a repetition of the first dose.
“If you get your first dose and don’t get your second dose for a couple of years, you probably need to repeat your first dose,” says Kang. “If it’s a matter of weeks, you definitely don’t have to worry. Even if it’s a matter of months, you most likely don’t have to.”
Can pregnant/lactating women take the vaccine?
It is absolutely safe for pregnant and lactating women to take vaccines, says Kang. Although there have been no trials for Covid vaccines, large-scale vaccination campaigns in the past have included pregnant women and new mothers. Additionally, large numbers of pregnant healthcare workers globally have taken the vaccine already.
Antibodies induced by the vaccine (or infection) can also pass on to the foetus through the placenta. Only IgG antibodies pass through, and the most transfer occurs in the second trimester and early third trimester. Maternal antibodies in children protect for about four to six months, after which their own immune system’s efficiency improves rapidly.
Antibodies also pass through breast milk to an infant, but these are IgA antibodies that protect the gut and not the respiratory tract — the part of the body that is adversely affected by the coronavirus.
Can I take the vaccine if I have allergies? Are there any conditions that require not taking the vaccine?
The only people who should not take the vaccine are those who have already taken the vaccine and had a severe allergic reaction to it, says Kang.
There is no evidence right now that identifies any kind of allergy to a food or a drug and associates it with the vaccine. The vaccine is safe for people with all kinds of food allergies, as well as drug allergies, including allergies to antibiotics such as penicillin.
Immuno-compromised patients and those undergoing chemotherapy are also safe to take the vaccines. However, as they are immunosuppressed, they might not make as good an immune response as others.
Do antibody tests work after vaccination?
IgM and IgG antibodies are binding antibodies as they physically bind their Y-shaped structure to the proteins on the virus, flagging it and causing macrophage cells to destroy it. They can also cause natural killer cells to come destroy cells that are infected with the virus. They simply act as markers and do not interfere with the infectivity of the virus.
There is another group of antibodies called neutralising antibodies. These too bind to the proteins on the virus, but they can also affect the ability of the virus to infect host cells by preventing the virus from undergoing structural changes required to gain entry.
At the moment, we do not know which antibody between IgG and neutralising antibody plays the larger role of protection against the virus but it is likely neutralising antibodies, think experts.
However, we do not know that for sure and we also don’t know what level of protection they provide, explains Kang. To identify this, we would need to study breakthrough infections (those who got infected after vaccination).
Antibody tests on the market today measure IgM and IgG antibodies, which are also always produced when the immune response is triggered — whether after natural infection or after vaccination. We do not have a standardised neutralising antibody test.
“So antibody tests after vaccination don’t look at the right thing,” Kang says. “Commercial tests are only binding antibody tests. They tell you [if] you have been infected or vaccinated, but they don’t tell you whether you are protected or not.”
How long after the Covid shots should I take other vaccines?
Our immune systems are quite capable of handling multiple infections and don’t easily reach a point of exhaustion with just one infection, says Kang.
“The objective is to maximise immune response,” she adds. “The general guidance is that if two vaccines are to be given — live vaccines in particular — they should be given together or separated by four weeks.”
(Edited by Manasa Mohan)
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