One explanation for virus not behaving as expected could be previous exposure to other infections, experts tell MPs
The coronavirus pandemic has peaked earlier than expected in many African countries, confounding early predictions, experts have told MPs.
Scientists do not yet know why, but one hypothesis is the possibility of people having pre-existing immunity to Covid-19, caused by exposure to other infections.
Prof Francesco Checchi, a specialist in epidemiology at the London School of Hygiene and Tropical Medicine, told MPs it was “broadly” true that coronavirus had not behaved in expected ways in African countries, including Kenya, Tanzania, Sudan and Somalia.
“We are certainly observing a pattern that confounds us a little,” he told the international development committee’s inquiry into the impact of Covid on humanitarian crises.
“In a few important case studies – Kenya, for example – what seems to be happening is the epidemic may be peaking earlier than our naive models predicted.”
He said a similar pattern has emerged in Yemen, which is in the middle of the worst humanitarian crisis in the world.
“Yemen is one of the few countries where to my knowledge there is almost no prevention of Covid transmission,” Checchi said.
“The anecdotal reports we’re getting inside Yemen are pretty consistent that the epidemic has, quote unquote, passed.
“There was a peak in May, June across Yemen, where hospitalisation facilities were being overwhelmed. That is no longer the case.”
It was possible that the population had accrued some sort of “herd immunity” at least temporarily, he said.
While that was “very good news”, Checchi said he was unable to say whether it had been less lethal or less severe on a per capita basis. In many developing countries, where testing is poor and deaths are not notified to the authorities, the rate of reported deaths is very low.
A study published on Tuesday from Imperial College London estimated that in Damascus, Syria, reported deaths from coronavirus were as low as 1.25% of the true figure.