Can You Get Reinfected With COVID After 2 Vaccine Doses? Experts Explain
What are your chances of catching COVID a second time after the first illness and 2 vaccine doses? FIT asks experts.
Recently, a study was published in the Medical Journal, Elsevier that followed the case study of a healthcare worker in India who caught COVID-19 for a second time after having had the infection once, and also being fully vaccinated.
This study, carried out by scientists in India, although an isolated case, is quite significant in that it throws up multiple questions about COVID reinfections, breakthroughs and what we know to be the combination that is said to elicit the strongest immune response.
What does this case study tell us about COVID reinfections? Does this mean the COVID virus is getting more virulent?
FIT speaks to the study's author, Dr Vinod Scaria, and renowned virologists Dr Gagandeep Kang and Dr Shahid Jameel for clarity on the matter.
The 'Hybrid Immunity'
Speaking to FIT for a previous article, experts explained how a 'hybrid immunity' gives the strongest immune response.
"The combination of immunity from past infection and vaccine elicited immunity appears to be the most robust immune response. Antibodies titers, memory responses and cellular responses were significantly higher in individuals with this 'hybrid immunity’," said Dr Swapneil Parikh, Internal medicine specialist, Mumbai.
But of course, there are always exceptions. And this is where this healthcare worker's case is significant.
The Case Study: What It Means
Key points of the study
The patient is a 28 year old healthcare worker in India.
He first tested positive for COVID-19 with standard, moderate symptoms of fever, breathlessness, sore throat, which lasted for around 7 days.
Antibody titres two weeks after testing negative on RT-PCR, revealed a moderate level of antibodies to spike protein.
He later took the full course (two doses) of Covishield COVID vaccine with a gap of 4 weeks.
A month after the second dose, he again developed symptoms of COVID and was tested positive. This time the illness lasted about 12 days with similar symptoms.
Genomic sequencing found the B.1.617.2 (Delta) variant's lineage to be the cause of both infections.
"The paper describes a rare case of an individual who had a previous infection + 2 doses of vaccine, and had a symptomatic re-infection," says Dr Vinod Scaria, the Principal Scientist CSIR Institute of Genomics and Integrative Biology (CSIR-IGIB), and one of the researchers involved in the study.
In fact, this is the first documented case of its kind.
"These cases are rare, since hybrid immunity (infection+vaccination) is supposed to provide a better immune response,"Dr Vinod Scaria, Principal Scientist, CSIR Institute of Genomics and Integrative Biology (CSIR-IGIB)
It is also interesting to note that, according to the study authors, this particular person did not have an immunodeficiency—which is the primary cause behind breakthrough and reinfections.
About this, Dr Gagandeep Kang, virologist and Professor at Christian Medical College, Vellore, says "with time, we should expect some decline in ability to protect against infections."
"For a mucosal infection it is near impossible to protect against infection forever, and it is a marker of how good the SARS-CoV2 vaccines are in that they protect against infection very well for a few months."Dr Gagandeep Kang, Virologist
Does this mean it is a matter of concern?
Not necessarily. Dr Scaria also believes that such cases are extremely rare.
Virologist, Dr Shahid Jameel, agrees.
"The case study is interesting but isolated. It documents that reinfection is possible, which is what we already knew," he says.
Dr Jamee also adds that, more than looking at individual cases, it is important to look at the response in the population on the whole.
"None of the vaccines protect against infection but protect against severe disease and mortality. And they are doing very well."Dr Shahid Jameel, Virologist
Virologist, Dr Gagandeep Kang reiterates this, saying, "Vaccine protect against death, severe disease (needing ventilatory support or ICU care), hospitalization, moderate disease managed at home, mild disease and infection in decreasing order of efficacy."
So although the vaccines are best at preventing death, their immune response is poorest against infection as we have establishing, leaving a window open for reifections and breakthroughs.
But that doesn't dimish the significance of the study, because even if it is an isolated and rare incident, it brings us one step closed to understanding the virus and how it behaves.
The SARS CoV 2 virus is ever evolving, and the only way to stay a step ahead of it is to keep an eye on the way it's evolving, especially when it comes to our first line of defense, that is the vaccine.
"As a significant population has been infected (suggested by seroprevalence studies) and as a large proportion of population gets vaccinated, it would be useful to look out for breakthrough infections, since they suggest unique properties of virus evolution to evade Antibodies and therefore would be interesting to look at virus evolution."Dr Vinod Scaria, Principal Scientist, CSIR Institute of Genomics and Integrative Biology (CSIR-IGIB)
"Newer virus lineages which can cause breakthrough infections in significant numbers would indeed be of interest to understand virus evolution as well as to be prepared and be on a lookout for the spread of such virus variants," he adds.
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