With the recovery rate above 65%, the Central and state governments are pushing Covid-19 survivors to become plasma donors. But, according to doctors, surviving corona doesn’t make an individual completely immune against the disease and relapse/recurrence of the deadly virus is still possible. Meanwhile, to make things more worrisome, a study conducted jointly by researchers at IIT-Bhubaneswar and the AIIMS has shown that the spread of Covid-19 may pick up its speed during monsoon and winter.
The rainfall, decrease in temperatures and cooling of the atmosphere coupled with progression towards winter may help the spread of the virus in the country, according to the study led by V. Vinoj, Assistant Professor of the School of Earth, Ocean and Climatic Sciences at IITBhubaneswar. The report— Covid-19 spread in India and its dependence on temperature and relative humidity—took into account the pattern of the coronavirus outbreak and the number of such cases in 28 states between April and June.
As for the relapse/recurrence of Covid-19, Dr Kavitha Manjunath, Clinical Head of Portea Medicine, said there isn’t substantial data available to show if individuals who have recovered are completely safe from reinfection. “It is likely that after developing a disease, the immunity can develop in most people. It is more likely that people will get relapses rather than re-infections, but various studies have said that there isn’t enough data to prove that re-infection is not possible,” she said. There are chances of re-infection and individuals who have once recovered from the disease need to continue following the safety guidelines laid down by the WHO, she added.
The WHO says that the development of immunity to a pathogen through natural infection is a multi-step process that typically takes place over 1-2 weeks. Medical professionals across the board agree that while a certain level of immunity does appear in survivors, it cannot yet be ascertained as to how long this will stay. “Most viral infections either persist like Hepatitis C or HIV or once they occur, they don’t occur again like chicken pox or measles. The latter is unless the strain is different. With very little data it is difficult to ascertain how long the immunity will last for Covid-19,” says Dr K.K. Aggarwal, president of CMAAO and HCFI.
The body responds to a viral infection immediately with a non-specific response to slow the progress of the virus and may even prevent it from causing symptoms. This non-specific response is followed by an adaptive response where the body makes antibodies that specifically bind to the virus. These antibodies are proteins called immunoglobulins. The body also makes T-cells that recognise and eliminate other cells infected with the virus. This is called cellular immunity. This combined adaptive response may clear the virus from the body, and if the response is strong enough, may prevent progression to severe illness or re-infection by the same virus. This process is often measured by the presence of antibodies in blood.
Dr Aggarwal says that while antibody tests are important as they talk about the body’s ability to fight a virus but they don’t exactly show the whole picture. “The antibodies we are checking are only for the spike protein. We are not checking for the whole virus. The spike is responsible for pneumonia but is it responsible for nonpneumonic symptoms, we don’t know,” he said.
While earlier coronavirus like SARS-CoV-1 have shown that a healthy human body can have created an immunity for up to two years, this new strain is still relatively new to the picture. Dr Vikam Sanghi, CEO of Sanghi Medical Centre, says, “There is hope that the immunity will last long enough till we find a vaccine but that cannot be said with certainty as there just haven’t been a conclusive study on this. My advice to everyone, corona survivor or not, would be to not take it too easy. Maintain social distancing, wear masks and wash your hands regularly.”
With agency inputs