As the speculation is rife that authorities might be considering the herd-immunity concept to get rid of the coronavirus pandemic, a former World Health Organization (WHO) official warned that it cannot be a strategic option in a densely populated country like Bangladesh.
In an interview with UNB, professor Muzaherul Huq, a former adviser for WHO South-East Asia region, also said thinking of attaining the herd immunity in Bangladesh is nothing but “stupidity and foolishness” as the country cannot afford its fallouts.
He thinks Bangladesh has no other alternative to following the COVID-19 appropriate behaviour and preventive measures as per WHO’s guidelines to slow the virus infection in absence of an effective vaccine.
“There’re two ways to eliminate coronavirus -- one is vaccination and another is herd immunity,” Muzaherul observed.
He said herd immunity allows a majority of the population to gain resistance to the virus by becoming infected and then recovering. “It’s an approach to depend on destiny for the life and death of people. Once a large proportion of the population gets infected (more than 70 per cent), then this would protect the rest from infection.”
The expert, however, said how long immunity persists varies based on the virus, and it is still not known how long the corona survivors might have that protection.
He said the UK and Sweden first had taken the herd-immunity approach to eliminate the virus, but the UK later abandoned it. “When a country depends on herd immunity, it puts a severe strain on its medical system and many of its citizens may die. So, Britain finally discarded the approach considering the consequences.”
Muzaheru said now Sweden is the only country in the world that is still trying to achieve herd immunity since the vast country has a very limited population.
“But Bangladesh is a densely-populated country with over 170 billion population. If we allow our 70 per cent people to get infected with the virus, many people, mainly elderly ones or who have co-morbidities will develop severe infections and will either die or need critical care at hospitals,” the health expert mentioned.
Besides, he said, Bangladesh can achieve herd immunity when at least 11 crore people expose to the virus. “So, we can’t want such a big portion of our population to be affected with the virus and put their lives at stake as our healthcare system is not ready to take such pressure or ensure treatment for them.”
Asked how many people may get infected with the virus by this time in the country as many experts cast doubt about the official data, he said it is difficult to say since the county’ testing capacity is very poor while many districts remain out of testing facility.
“The infection rate in the country is 20.46 against total tests carried out so far. So, we can assume, the maximum 20 per cent of the population has so far contracted the virus. If we want to achieve herd immunity, 50 per cent more people need to be caught by the virus. This is not a pragmatic option for us as we don’t have adequate healthcare facilities for our people, especially in rural areas,” the former WHO official said.
Chances of reinfection
Muzaherul said the people who exposed to the coronavirus usually produce immune molecules or antibodies. “But researchers across the world are still not sure how much time the antibody can protect one from getting affected the second time with the virus.
He said there were some cases of reinfection of the virus in some countries, including in South Korea, but experts later said it was the reappearance of the hidden symptoms, not the reinfection. “The symptoms of the virus may have disappeared or the virus may have secreted itself into certain parts of the body before one completely recover, and then resurfaced after some days or weeks. Besides, faulty tests and low presence of the virus can produce a false negative.”
He said there are some vaccines like pneumonia one work lifelong after taking a single dose while there are some other vaccines like influenza and hepatitis B ones that need multiple doses at different times. So, we’re still not sure whether corona behaves like pneumonia or like influenza.”
The health expert said antibodies do not develop at the same level in the bodies of all corona survivors. “Some corona patients produce plentiful antibodies while some other very low antibodies. “Antibodies also can disappear within a period of time. So, as long as the exact duration of antibodies will be proved scientifically, no one can rule out the chances of reinfection.”
He said there are some vaccines like pneumonia one work lifelong after taking a single dose while there are some other vaccines like influenza and hepatitis B ones that need multiple doses at different times. So, we’re still not sure whether corona behaves like pneumonia or like influenza.”
According to Michael Mina, an immunologist at Harvard University, it may be possible for the coronavirus to strike the same person twice, but it’s highly unlikely, reports the New York Times.
He said the coronavirus also provokes a vigorous defence from immune cells that can kill the virus and quickly rouse reinforcements for future battles. “Less is known about how long these so-called memory T cells persist — those that recognize other coronaviruses may linger for life — but they can buttress defences against the new coronavirus.”
Even after the first surge of immunity fades, Mina said there is likely to be some residual protection. And while antibodies have received all the attention because they are easier to study and detect, memory T cells and B cells are also powerful immune warriors in a fight against any pathogen.