World nowhere near herd immunity, says WHO as global cases hit 22 million
(SCMP) – The World Health Organisation says the planet was nowhere near the amount of coronavirus immunity needed to induce herd immunity, where enough of the population would have antibodies to stop the spread.
The remarks came as the global infection tally passed 22 million on Wednesday Hong Kong time, according to a tally by Johns Hopkins University. More than 780,000 coronavirus-related deaths have been reported worldwide.
The United States has recorded the most deaths – more than 171,000 – followed by Brazil, Mexico, India and Britain.
Herd immunity is typically achieved with vaccination and most scientists estimate at least 70 per cent of the population must have antibodies to prevent an outbreak.
But some experts have suggested that even if half the population had immunity, there might be a protective effect.
WHO’s emergencies chief Dr Michael Ryan largely dismissed that theory at a press briefing on Tuesday, saying we should not live “in hope” of achieving herd immunity.
“As a global population, we are nowhere close to the levels of immunity required to stop this disease transmitting,” he said. “This is not a solution and not a solution we should be looking to.”
Most studies conducted to date have suggested only about 10 per cent to 20 per cent of people have antibodies.
Dr Bruce Aylward, a senior adviser to WHO’s director general, added that any mass immunisation campaign with a Covid-19 vaccine would aim to cover far more than 50 per cent of the world’s population.
“We don’t want to be wrong,” he said. “You want to plan to get high coverage and not get lulled into a dangerously seductive suggestion that [the herd immunity threshold] could be low.”
The WHO wrote to every country on Tuesday urging them to quickly join its global shared vaccine programme – and spelled out who would get its eventual coronavirus jabs first.
The WHO’s director general Tedros Adhanom Ghebreyesus said that without vaccinating the planet’s highest-risk populations simultaneously, it would be impossible to rebuild the global economy.
And he said the most exposed 20 per cent of each country’s population – including front-line health workers, adults over 65 and those with pre-existing conditions – would be targeted in the first wave of vaccinations, once the WHO-led Covax shared facility can roll out a proven safe and effective vaccine.
“The fastest way to end this pandemic and to reopen economies is to start by protecting the highest risk populations everywhere, rather than the entire populations of just some countries,” Tedros told a virtual press conference.
Researchers and pharmaceutical giants are racing to produce a vaccine, with nine of the 29 currently being tested on humans forming part of the Covax Global Vaccines Facility.
Some 92 countries are signed up to Covax – an effort to pool the costs and rewards of finding, producing and distributing effective vaccines – while a further 80 have expressed interest but are yet to commit fully.
The WHO wants countries to signal a firm interest by August 31.
Calls for coordinated action on vaccines came as some nations dealt with new outbreaks.
South Korean health workers have found more than 600 infections linked to a Seoul church led by a vocal opponent of the country’s president as officials began restricting gatherings in the greater capital area amid fears that transmissions are getting out of control.
The country on Wednesday reported 297 new cases of the virus, its biggest daily rise since March 8.
It was the sixth straight day the country reported daily increases in triple digits, with most of the cases coming from the densely populated Seoul metropolitan area.
Elsewhere in the Asia-Pacific region, India reported 1,092 new deaths, its highest single-day total and authorities imposed a one-week lockdown in Nepal’s capital Kathmandu and surrounding districts after a surge in cases.
New Zealand appeared to be gaining control over a coronavirus outbreak in Auckland after just five new community infections were reported amid record levels of testing and contact tracing.
The discovery of an outbreak last week prompted authorities to put the nation’s largest city into a two-week lockdown.