Next Covid-19 test? Diagnostic blind spots stir visions of bleak midwinter
- Patchy vaccination coverage threatens efforts to keep the coronavirus at bay, while relaxing restrictions may bring a rebound in cases
- But dangers posed by new variants may be multiplied by poorer countries lacking the resources to detect them
Vaccination drives around the globe have shown varying progress, while even countries that have largely inoculated their populations and contained their outbreaks could find their success undone by a lack of resources in others.
Poorer countries’ weaker testing capability, for example, has created “blind spots” in the world’s ability to detect and guard against dangerous new variants, said Jerome Kim, director general of the International Vaccine Institute.
“I worry about the winter,” Kim said. “There are too many places, too many people, who are not vaccinated and who probably won’t be vaccinated by December. In countries with high vaccination rates there are often pockets of unvaccinated people.”
With over 2.19 billion shots in arms, China has fully vaccinated 78 per cent of its population
In the United States, about 58 per cent of the population has been vaccinated, but relatively high mortality rates have been reported in communities where vaccination rates are low. Last Wednesday, for example, the country recorded over 2,200 deaths caused by Covid-19.
But even if those areas of low vaccination were to administer more jabs, inadequate testing resources in other countries presents a threat to everyone, Kim said.
“Outbreaks yield variants, although vaccination prevents outbreaks and lowers variant generation,” he said.
“We are expecting a surge in the northern hemisphere because of the seasonality of viruses, a high percentage of people being susceptible to the Delta variant, and relaxation since there is now a decline [in infections] in many of these countries,” said Ali Mokdad, a professor of health metrics sciences at the University of Washington.
Vaccines have proved to be effective in cutting hospital admissions and deaths, though not as effective in reducing transmission, but waning immunity of early recipients of vaccines in places such as the US and Europe may make the population more susceptible to another outbreak.
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“Waning immunity is a major concern because many studies have shown that immunity against infection goes down with time, and there is a need for a booster six months after the second dose for Pfizer and other vaccines,” Mokdad said.
Some experts and policymakers have expressed worries about the possibility of Covid-19 and flu spreading simultaneously in winter, in what some call a “twindemic”.
Incidences of seasonal flu dropped in many places last winter because of mask wearing and social distancing, but as many countries are relaxing such rules, experts have urged the public to get flu shots.
Jenny Harries, head of the Health Security Agency in the UK, told national broadcaster the BBC that the country was facing “an uncertain winter” with people at “more significant risk of death from serious illness if they are coinfected with both viruses”.
“There is a high risk of a winter Covid-19 surge in most countries in the northern hemisphere, especially for countries such as India where the uptake of vaccination remains low,” said Vincent Pang Junxiong, director of the Centre for Infectious Disease, Epidemiology and Research at the National University of Singapore.
The emergence of new variants is still possible, although many areas have high levels of vaccination, Pang said.
“It should be noted that a high coverage of vaccination, with herd immunity achieved, is only likely to slow down the speed of emergence of new variants significantly,” he said.
Some Asian countries have made headway in their vaccination drives and are gradually relaxing social distancing restrictions and reopening borders, but others, including China, are resisting.
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Singapore has over 80 per cent of its population vaccinated and it is gradually opening its borders. But local cases jumped on Tuesday and the government opted to scale back social interaction for two weeks.
Malaysia announced this week that it would resume interstate and outbound international travel after vaccinating 90 per cent of its adults.
Despite its high vaccination rate, China has been monitoring how increased mobility among its neighbours is reflected in numbers of imported infections.
Vice-Premier Sun Chunlan told a meeting in Beijing last Monday that relaxed containment measures and cross-border travel restrictions elsewhere posed new challenges for China.
Some countries have opened up because their hospital admissions and death rates have fallen – among the benefits of vaccination.
Speaking at a conference last Tuesday, Zhang Wenhong, director of the department of infectious diseases at Shanghai’s Huashan Hospital, highlighted a “breakthrough rate” of infection that was high in places with high vaccination rates.
“That means many people are infected even though they have had two doses, and there will be more infections among people who have had two doses in the future,” he said.
“Over 80 per cent of people in Singapore are vaccinated, but we don’t see any sign that the outbreak is stopped. We see a rise in the number of infections as Singapore gradually opens up.”
The breakthrough rate in the US had reached 36 per cent, according to data released in late August, he said.
Zhang said China opening its border would depend on its ability to stop Covid-19 spreading. China is one of the few countries to have stuck to a zero-tolerance policy.
Some countries, including China, have rolled out boosters to high risk groups.
The United States has authorised Pfizer booster jabs for those over 65 or at high risk of severe illness, as well as frontline workers. It is also considering whether to authorise Moderna and Johnson & Johnson boosters.
The Europe regulator also backed booster shots for those at high risk.
China’s response to the recommendations was low key, but many provincial authorities have started giving boosters to high risk groups and any individuals who wish to have a third jab.
By Friday, more than 2.2 billion doses had been administered and 1 billion people had been fully inoculated, according to the National Health Commission.
In recent months, some countries, such as the United Arab Emirates and Indonesia, that used inactivated vaccines by Chinese firms Sinopharm and Sinovac, have announced third doses of various technologies to boost protection for the elderly or health workers.
A big unknown is whether a new variant trickier to contain than the Delta variant will emerge.
John Moore, professor of microbiology and immunology at Weill Cornell Medical College in New York, highlighted the hidden danger of the unknown mutations that may yet emerge.
“Could a virus arise that has got the transmissibility of Delta and the antibody resistance of Beta?” he said. “It’s possible – we don’t know. That would be much more of a concern.”
Illustration: Lau Ka-kuen