While talking about his bout with the coronavirus in the final presidential debate held on 23 October, United States President Donald Trump said that he might be immune from the virus.
“And now they say I’m immune. Whether it’s four months or a lifetime, nobody’s been able to say that, but I’m immune,” he said in the debate.
He has made the same claim previously in multiple interviews, campaign rallies and on Twitter. The social media giant, however, added a warning label to his tweet and said that his tweet “violated the Twitter Rules about spreading misleading and potentially harmful information related to COVID”.
Coronavirus Reinfections
To understand more about why this could be misleading, we took a look at confirmed COVID-19 reinfection cases and our immune response to the virus.
The first confirmed case of reinfection was recorded in Hong Kong where a 33-year-old man tested positive for the virus after having fully recovered four and a half months ago. The second infection was mild and asymptomatic.
Studies conducted by researchers from the University of Hong Kong’s Li Ka Shing Faculty of Medicine Department of Microbiology found that the patient’s two episodes were caused by virus strains with clearly different genome sequences, that was published in the British Medical Journal in August.
The Lancet published a report on 12 October 2020 where it confirmed the first confirmed case of coronavirus reinfection in the US.
The 25-year-old Nevada man - the patient in question - tested positive for COVID-19 first on 18 April and the second time on 5 June, separated by two negative tests done during a follow-up in May. Genomic analysis of the virus showed genetically significant differences between each variant associated with both instances of infection.
Contrary to what was seen in the Hong Kong patient, the US patient showed increased symptom severity in their second infection.
Immune Response
Most COVID-19 patients who recovered have antibodies to the SARS-CoV-2 virus detectable in their blood in about 1-3 weeks after the symptoms start, said a WHO report.
The immune response is caused mainly by 3 things - antibodies, B cells and T cells. B cells produce antibodies that are specific to a particular virus while T cells kill the virus that has entered the cells in the human body.
Once the infection is over, the T cells and B cells decline in number, but some cells will remain, which are called the memory cells. They respond rapidly if they come in contact with the same virus again, killing the virus and accelerating an antibody response.
Patients who have had more severe disease appear to have higher levels of important neutralising antibodies, the report said.
But in mild cases, fewer antibodies are developed a study in JAMA shows that they might disappear after three months.
What Does This Mean for a COVID-19 Vaccine?
At least four cases of reinfection have been confirmed around the world, which suggests that previous exposure to the virus does not guarantee total immunity, the Lancet study notes.
More importantly, this could mean that people who have once recovered may still be at risk and could also need to get vaccinated.
We reached out to celebrated virologist and former professor at the Christian Medical College, Vellore, Dr T Jacob John who told us that these cases of reinfections were extremely rare and vaccination will still work. He further added that the immune response in the patients with confirmed reinfections was required to be studied in detail to understand the causes.
Even though vaccines continue to remain crucial in our fight against the virus, following all other precautions such as washing hands, wearing masks and maintaining distance remains non-negotiable with looming questions of COVID-19 immunity and how long it lasts.
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