BENGALURU: If you recover from Covid-19, your immunity will last for at least six months. But the bad news is that you can still carry the virus and infect others, as herd immunity still a distant dream.According to Health Department officials and epidemiologists, herd immunity can be attained only when 60% of the population contracts the disease and recovers. “But there is a long way to go. At present we are relying on sero-survey reports and focusing on individual and community immunity to fight the virus.
Though there is no medical research, since the virus is new, chances are that a person is immune to the virus for six months. They are important in breaking the chain and can help build community immunity,” said a health official.“Immunity is the best way to beat the virus. Herd immunity will take longer, because at least 50-60 per cent of the people need to get infected.
The sero-prevalence report as on September 28 shows that 7.5 per cent have been infected and cured in India. In Karnataka, even if we presume that the population of Bengaluru is 100 lakh, the reported positives constitute 2.28 lakh (2.3%). So individual immunity and community immunity is the way forward at the moment,” a senior BBMP official said.
Dr Smitha S from Victoria Hospital said antibodies created while fighting the virus last for 4-6 months. But so far, people have not been tested to know how many antibodies are there. Dr Giridhar Babu, member of Karnataka Expert Committee, said that while there is no absolute confidence, since the number of relapses is very less, it is understood that immunity last six months. The government has begun focusing on new areas where many cases are being reported. Sero-survey reports are awaited to help channelise the way forward.
BRAZILIAN CITY CASTS DOUBTS ON ‘HERD IMMUNITY’?
The experience of Manaus, the largest city in Brazil’s Amazon basin, suggest herd immunity may not last very long. Manaus witnessed a sharp fall in the number of deaths from about 60 a day on April 30, to just three by late August. The fall in the number of infections was attributed to herd immunity, with about 70 percent of the city’s population recording antibodies against the virus in March-April.
But the surge in Covid-19 cases and deaths is on the rise again, forcing authorities to reinforce a 30-day lockdown. A Sao Paulo University study raises questions about the concept of herd immunity for Covid-19. “Something that is evident in our study is that antibodies against SARS-CoV-2 decay quickly, a few months after infection,” Lewis Buss, one of the authors of the study, said in a statement by the São Paulo research foundation.