STUDY ON RE-INFECTION

SAnother study found that a 33-year old man who recovered from Covid-19 in April was re-infected in August. The viral genome from the first and the second infections were sequenced, studied and found to be genetically distinct. Interestingly, the second time he was infected, he remained asymptomatic, and his immune system kicked in cientists have found the answers (or the beginning of answers) to two important questions about Covid-19.

The first: why are men who contract the coronavirus disease at greater risk than women?

The answer — like many others where Covid-19 is concerned — lies in the immune response to the virus.

According to research by Akiko Iwasaki and others at the Yale School of Medicine, the male immune response is largely built around cytokines and chemokines, both signalling proteins that are part of the body’s immune response. The female response, the research, published in Nature says, is driven by T-cells, a major (and stronger) component of the immune system. The research offers the first plausible answer on why the mortality rate among infected men, especially those over the age of 60, is higher than that among infected women. As an aside, those interested in the more scientific aspects of Covid-19 would do well to follow Iwasaki’s work — she is among the clearest thinkers on many aspects of the disease.

The second question: can someone cured of Covid-19 be re-infected?

There have been many false starts to this answer, including some local ones, but according to a paper published on August 25 in the journal Clinical Infectious Diseases, the answer is yes.

The paper is based on research by doctors and scientists at the University of Hong Kong and speaks of a 33-year old man who recovered from Covid-19 in April, and was re-infected in August. The viral genome from the first and the second infections were sequenced, studied and, found to be genetically distinct. This wasn’t simply a residual infection — it was a new one. Interestingly, the second time the man was infected, he remained asymptomatic, and his immune system kicked in, producing new antibodies.

HT reported the Hong Kong incident soon after it happened, but there is a larger (and a related) learning in the two studies for vaccine developers. The first study (the one on gender differences) shows that they will have to factor in gender while developing vaccines to ensure that these are effective across the population. The second study shows that being infected once does not always rule out a re-infection — more research is needed, but, in general, it still could in many cases. This isn’t necessarily a blow for administrators and health care workers in regions hit hard by Sars-cov-2, the virus that causes the coronavirus disease, who were hoping that the high prevalence of the disease, as measured by antibody surveys, bestowed some level of immunity on the population. That could still be the case — but it cannot be taken for granted. Typically, this is also one of the things vaccines are tested for — not just whether they can provoke an immune response against the disease, but whether they can prevent a re-infection.

The need to answer questions such as these is why vaccine development usually takes years. The global health and economic crisis caused by the Covid-19 pandemic has meant that vaccine developers have tried to shorten the development cycle — something that could have a bearing on the efficacy of the vaccines or the length of the protection they offer (but that’s another story).

Nature’s website recently published a telling story (and graphic) on the extent to which the world is counting on the vaccines under development. Based on data from Airfinity, a research firm, the article said countries have struck deals or announced commitments for almost 4.5 billion doses of vaccines from nine vaccine developers. The UK, the article points out, has committed to buying 340 million doses. Its population is a little less than 70 million. The US, the European Union, and Japan have also committed to buying enough to vaccinate every one of their residents at least once, according to the article. India recently set up a committee to discuss various aspects of its vaccine strategy, from funding and sourcing to storage and delivery, but the global rush for vaccines only highlights the need to finalise this soon.