Covid-19: Herd immunity is not a safe bet for taming virus

What is herd immunity? I understand that a community manages to defend itself against the onslaught of a virus by a slow process of immunisation.

Herd immunity is the word that intrigued me ever since the pandemic struck in the beginning of this year. This magic word is bandied about whenever we talk about the end-game of the ongoing health crisis.

What is herd immunity? I understand that a community manages to defend itself against the onslaught of a virus by a slow process of immunisation. And this process can happen either by way of vaccination or natural exposure of the population to the virus so that a sufficient number of people develop resistance. No consensus exists among experts on what percentage of people should get infected before a community gets to develop herd immunity, the holy grail of epidemiology. Experts also say the threshold of the herd immunity varies from infection to infection. The more contagious it is, the higher the threshold.

Vaccination is the best way to achieve the herd immunity with the least impact in terms of loss of human lives. Pfizer, Moderna and Oxford-Astrazeneca unveiled the results of the advanced trials of their vaccines which showed high levels of effectiveness. Though they still await regulatory approvals, the vaccine manufacturers are racing to produce and store millions of vaccines. Head of the US coronavirus programme Dr Moncef Slaoui says the first jabs could be administered as early as December 11. So, there is all-round optimism on the vaccination front. Hopefully, we should be able to vaccinate enough number of people in the first quarter of the next year so that we can stop the rapid spread of the disease and attain some kind of a herd immunity.

There is a school of thought which calls for exposing the entire population to the latest strain of coronavirus naturally so that they develop herd immunity. Let the virus run through the entire population so that people get to develop immunity is the crux of this argument. But World Health Organisation chief Tedros Ghebreyesus calls this approach ‘scientifically and morally problematic’. Reacting strongly to what is generally perceived as a reckless approach, the WHO chief said herd immunity is achieved by protecting people from a virus, not by exposing them to it. “Never in the history of public health has herd immunity been used as a strategy for responding to an outbreak, let alone a pandemic,” the WHO chief pointed out.

Despite the WHO boss taking unequivocal stand against it, the idea of herd immunity continues to have some attraction to US President Donald Trump and his aides. Though there were occasions when the White House and its spokeswoman denied harbouring the idea, Trump continued to believe only the old with co-morbidities must be protected and the young and healthy should resume work so that the economy can be brought back to life. President-elect Joe Biden is ready to bury this strategy and is expected to adopt a more pro-active approach shaped by the best expert advice.

The idea the virus should be allowed to run through so that resistance is built among population is particularly galling to some. Philip Bump of Washington Post compares this to the local fire chief saying the house fire is over because it is burning itself out. So why bring the fire tender and spray water on the raging blaze when it will anyway burn itself out soon. This approach of staying silent as virus burns itself through the community can result in a huge death toll and is a morally questionable strategy.

Sweden’s case is often cited in any debate on herd immunity. The Scandinavian country did not have any of the restrictions that the other European nations had during the first phase of lockdowns. It does not even make mask wearing compulsory, though it called for social distancing in public places. It recorded huge number of deaths, especially among the elderly in the first phase of the pandemic. But in the subsequent second phase, it seems to be doing well. But epidemiologist Anders Tegnell who spearheaded the Sweden’s effort and earned a lot of fame denied their approach is to let the virus rampage through the community. They wanted to slow the spread without resorting to extreme lockdowns, disturbing the normal life. Their aim was to run the normal life as normally as possible. The jury is not yet out on this approach, though Sweden seems to be doing better than other European nations.

India and Pakistan too seem to be doing well after going through some rough patch. Islamabad turned the corner very early with Prime Minister Imran Khan claiming credit for his ‘smart lockdown’ approach. Huge casualties were initially expected in the two dense Asian nations because of the uncontrollable nature of crowds and streets.

India has not had a good time. It went through a very bad phase with experts making dire predictions that it would gallop past the US with the largest number of cases and deaths. But that does not seem to be happening anytime soon. After experiencing a peak in mid-September, the cases and deaths now are heading south. Despite an early lockdown, the rules were eased much before cases peaked. Social distancing, mask wearing and other protocols are being followed only in breach. But mysteriously there has been a sudden shift for the better in the virus trajectory in both these countries.

Is hidden immunity developed in Pakistan and India? Is it the cause of the unexplained slowdown in the spread of the virus? The anti-virus efforts and the hospital infrastructure are anything but exemplary in these two countries, though both the governments are quick to take credit for themselves. And both countries officially do not believe in herd immunity. They just want to stop the spread of the virus until a vaccine comes about.

All eyes are on how soon we can get back to normal life now that vaccines are on the way. With a section of population already developing some immunity after massive numbers of infections, it should be possible to vaccinate people to an extent where it is possible to stop the spread of the virus. Despite the optimism, it is still no time to let the guard down. It might take a while to roll out vaccinations across populations once regulatory approvals are obtained. Mask-wearing and social distancing protocols may stay on for some time until it is assured that vaccinations are succeeding in stopping the spread of the infection.

— sreenivasa@khaleejtimes.com