As Europe and the U.S. prepare to turn the page from the emergency stage of the coronavirus pandemic, countries once deemed winners for using strict measures to contain COVID-19 cases could face long-term challenges dealing with the virus.
A new surge in China driven largely by the omicron BA.2 subvariant led authorities to once again turn to their “zero tolerance” strategy, locking down cities and ordering people in certain provinces to stay home.
What Is ‘Zero COVID’ And Which Countries Have Adopted It?
Strict policies widely known as “zero COVID” or “zero tolerance” were adopted by some countries in Asia, as well as New Zealand and Australia, to keep virus levels low, or even zero. Measures included tracking and tracing every known case, closing borders and locking down cities.
The only country currently pursuing zero COVID is China, with Hong Kong signaling it is now pivoting away from such measures.
Is ‘Zero COVID’ Still An Effective Strategy?
Scientists increasingly question the effectiveness of the strategy against a highly transmissible variant like BA.2.
“I think ‘zero COVID’ may have served a purpose for some countries and they did very well,” Ravindra Gupta, professor of clinical microbiology at the Institute for Therapeutic Immunology and Infectious Diseases at the University of Cambridge, told HuffPost. “But I think omicron is showing us that it’s going to become increasingly difficult for them to maintain that strategy.”
Even Hong Kong, which has sought to stay in line with China’s strict policies on COVID until now, will begin easing some restrictions as the current wave peaks.
Hong Kong Chief Executive Carrie Lam said Monday she would lift a flight ban to nine countries, including the U.S., reduce the quarantine period for arrivals and abandon a previously announced plan for citywide mass testing, according to The Associated Press.
Chinese authorities also have reportedly signaled they are preparing to slowly relax the policy, but for now are sticking with zero COVID measures.
New Zealand, another country that scrapped zero COVID, announced it would open its borders to travelers from Australia on April 13 with no quarantine requirements, even though cases are on the rise. The country will also allow vaccinated travelers from 60 countries starting May 2, as long as they also present a negative COVID test, according to the BBC.
What Are The Risks Of Ditching ‘Zero COVID?’
The varying responses to omicron BA.2 also can be traced to differences in vaccination coverage and the types of vaccines being used.
For China, moving past zero COVID could prove easier said than done.
China has relied on domestically produced jabs — mostly Sinovac and Sinopharm, which are made from inactivated viruses — to inoculate its population. Inactivated vaccines use a killed version of the germ that causes the disease to produce an immune response, according to the U.S. Department of Health and Human Services. Early studies suggest Sinovac and Sinopharm are less effective against the omicron variant, even with three doses, than they are against earlier versions of COVID, according to Nature.
Chinese officials said Friday they have adjusted some vaccines to target omicron and delta, but the tuned versions still await safety and efficacy checks.
Only half of China’s over-80s have been vaccinated. In Hong Kong, 63% of over-80s are still unvaccinated, according to Bloomberg.
Gupta said China should carefully consider whether it wants to continue vaccinating its population with inactivated vaccines.
“I think that there needs to be a shift towards them achieving very high coverage of vaccination with vaccines that are shown to have really good, robust, durable responses,” Gupta said. “But it may take a period of transition, which means that they can continue the way they’re going, whilst they’re vaccinating the population effectively before then changing their policies.”
Dr. Peter Hotez, co-director of the Center for Vaccine Development at Texas Children’s Hospital, said historical lessons from measles and smallpox suggest the most effective way to halt transmission in China would involve vaccinating the population with a heterologous vaccine booster, which means a different vaccine than the ones used in the primary course of vaccination.
China could “improve the performance features of the whole inactivated virus vaccine through a heterologous boost, and try to achieve 90% vaccine coverage,” Hotez said. “And if they can do that I think that will help also a country withstand future variants.”
Is The Absence Of Herd Immunity In Countries That Used ‘Zero COVID’ A Problem?
Criticism of zero COVID usually includes an argument that countries that have followed such policies lack herd immunity from natural infections. Scientists are not convinced.
Hotez said natural immunity in people who have recovered from COVID has not been effective against new variants, but getting vaccinated on top of it can really help.
“Natural immunity with coronavirus from my viewpoint has not been very durable,” Hotez said. “And so far, I don’t think we’ve really seen any evidence of herd immunity from a lot of people infected. I think that was an original hope.”
What Is The Best Strategy For Countries Going Forward?
With cases on the rise in the U.K. as BA.2 spreads and restrictions are eased, some people are getting COVID for the first time.
Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, said the U.S. also may see an uptick in COVID cases in the coming weeks.
Hotez called on the U.S. government to create a vaccine advisory group to look into the technology of mRNA vaccines, which the U.S. and many other countries have relied on to curb the pandemic. Unlike traditional vaccines that use killed viruses, mRNA vaccines like the widely used Pfizer and Moderna shots teach cells to create a protein that triggers an immune response.
“The big unknown is whether this problem of short-term protections [is] omicron-specific or whether it’s a limit of the technology — that it’s good for going into epidemic situations, to vaccinate quickly and stabilize the situation for a year or two. But over the long haul, we may need something different,” Hotez said.