A Covid-19 lesson for the U.S. from three countries with rapid vaccination launches

Epidemiologists say the risk is real of a so-called exit wave of new infections, as countries leave the guard as shots increase, as vaccines do not offer 100% protection against the Covid-19 contract. New coronavirus variants that can elude immunity conferred by vaccination or past infection increase the risk of another surge.

They ease the restrictions too quickly and the virus will seize its opportunity, scientists say.

“We’re in a kind of walking race between vaccination and the virus,” said Graham Medley, a professor of infectious disease modeling at the London School of Hygiene and Tropical Medicine.

However, even with a new wave of infections, scientists are optimistic that broad vaccination coverage should provide significant protection against serious illness and death. Data from all three countries show that the risk groups that were given priority for vaccination remain, for the most part, disease-free.

So far Israel has administered at least one dose of vaccine to 62% of its population, the United Kingdom to 48% of its residents and Chile to 40%, according to health ministries and data collected by the Our World in Data project. Oxford University.

The United States has administered one or more shots to 39% of its population and the 27 members of the European Union have vaccinated together only 18% of their own.

Israel offers a lesson on what happens if vaccination outpaces the virus. The country was averaging more than 8,000 new infections a day at the peak of its last big wave in mid-January. There are now hundreds of new cases. Some Israeli hospitals, including the country’s largest medical center, Sheba, have begun closing their Covid-19 treatment rooms.

Residents wrapped up in bar restaurants as the Israeli economy reopened in March and students returned to classrooms, causing concern for another impending wave.

Instead, cases continued to dwindle, suggesting that widespread immunity to vaccination or past infection keeps a lid on the spread of the virus.

“A lot of people, including us, said we might have another wave in March,” said Eren Segal, a computer biologist at the Weizmann Institute in central Israel and a member of a government civil advisory committee on issues of coronavirus. “We’re very happy it hasn’t happened so far.”

Professor Segal said that in the summer there will be even less chance of a resurgence, as Israel is expected to have already vaccinated many of its young people aged 12 to 15, further reducing the size of the susceptible population. An extensive testing program aims to keep the virus under control in younger children. Now researchers say they do not expect further rises in infections unless a vaccine-resistant variant enters the country.

Chile’s vaccination campaign has been a bright spot in Latin America, as its neighbors struggle to get their own shots while being attacked by a second wave of infections.

But the country is struggling with an increase in new infections that forced the government of President Sebastián Piñera to implement a new closure, close borders and postpone elections scheduled for this month. New coronavirus cases rose to over 9,000 a day this month, the highest daily total, making hospitals in capacity with an influx of younger patients.

Health experts say the rise in infections highlights the risk of easing social restrictions before inoculating enough people to prevent the spread of the virus and the threat of variants such as P.1, identified by first time in Brazil.

Some epidemiologists say Chile went too fast to celebrate its rapid implementation of vaccinations. As officials eased the restrictions, residents lowered their guard on measures such as masked clothing, hand washing and social distancing, believing the pandemic would end soon, said Claudia Cortés, an infectious disease expert from the University of Chile.

“They gave the wrong message,” he said. “For the general population, it was very confusing.”

Chile has also relied heavily on China’s Sinovac vaccine, which the Chilean government said last week was only 16% effective in reducing the risk of infection after a shot and 67% effective two weeks after the second dose.

Officials and doctors say vaccines are starting to work. Although cases are increasing among people under the age of 60, infections are beginning to decline for high-risk seniors, whose deaths have been reduced, according to government data. The two-dose regimen is 80% effective in preventing death from Covid-19, the government said.

“There is now a clear trend that we can see with the separation of curves between those over 70 and young people, who are just starting to get vaccinated,” said Miguel O’Ryan, a public health expert at the University. of Chile. .

UK officials, who are struggling with vaccine supply problems as they draw a route out of a strict blockade needed to control the contagious variant B.1.1.7 first detected in England, see Chile’s experience as a precautionary tale. The country has suffered the highest number of deaths in Europe and scientists and public health experts advising the government urge the slow and gradual release of restrictions to ensure vaccinations continue to outpace the virus.

Disease modelers who advised the UK government have looked into the possible course of the pandemic over the next year if restrictions on the economy and daily life are reduced, according to the four-step roadmap of the Prime Minister Boris Johnson who is not blocked.

His work highlights the risk of a surge, with a model by epidemiologists at Imperial College London suggesting that the UK could face five million more cases by June 2022 if they relax. the controls as planned. This exceeds the four million known cases already recorded, although deficiencies in initial pandemic testing mean that the true total number of infections is probably much higher.

According to the models, vaccination means that hospitalizations and deaths from Covid-19 will be much lower than previous pandemic outbreaks. But they remain substantial, with the Imperial model, for example, reporting up to 15,700 more deaths by June 2022. To date, the UK has suffered 150,000 deaths with the Covid-19 mentioned in the death certificate.

A group of scientists advising the government said in a report that the size of any output wave will be hugely sensitive to issues such as the speed and level of vaccine uptake, any supply hiccups and the still uncertain role they play. warm weather and summery behavior. by limiting the spread of the virus.

Another critical factor is the effectiveness of vaccines in preventing transmission, beyond preventing infection or serious illness.

A vaccine that is highly effective in stopping transmission would probably mean far fewer cases and very few deaths, said Professor Medley, who is part of the advisory panel.

Scientists are still collecting data on the effect of vaccines on the spread of the virus. Studies from Israel and the United Kingdom suggest the vaccine developed by Pfizer Inc.

and BioNTech SE is highly effective in preventing subsequent transmission.

Write to Jason Douglas to [email protected] and Ryan Dube to [email protected]