A Covid-19 lesson for the US from three countries with rapid vaccination launches

Epidemiologists say the risk is real of a so-called wave of new infections, as countries are on guard as fires increase, as vaccines do not provide 100% protection against contracting Covid-19. New variants of coronavirus that can steal immunity from vaccination or past infection increase the risk of further growth.

Reduce restrictions too quickly and the virus will seize its chance, scientists say.

“We are in a kind of 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 severe disease and death. Data from all three countries show that at-risk groups given priority for vaccination are, for the most part, disease-free.

Israel has so far given at least one dose of vaccine to 62 percent of its population, Britain to 48 percent of its residents and Chile to 40 percent, according to health ministries and data compiled by the Our University in Data project at Oxford University.

The United States administered a single blow to 39% of its population, and the 27 members of the European Union vaccinated only 18% of them.

Israel offers a lesson on what happens if vaccination goes beyond the virus. The country was on average over 8,000 new infections a day, at the height of its last big wave in mid-January. The new cases are now in the hundreds. Some Israeli hospitals, including the country’s largest center, Sheba Medical Center, have begun closing Covid-19 treatment facilities.

Residents packed into restaurants in bars, while the Israeli economy reopened in March, and students returned to classrooms, worrying that another wave was imminent.

Instead, cases have continued to decline, suggesting that widespread immunity to vaccination or previous infections is keeping 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 the government’s civil advisory committee on coronavirus problems. . “We are very happy that it has not happened so far.”

Prof. Segal said that by the summer there will be even less chance of recurrence, as Israel should have vaccinated many of its children aged 12 to 15 by then, further reducing the size of the sensitive population. An extensive testing program aims to keep the virus under control in younger children. Researchers now say they do not expect further increases in infections unless a vaccine-resistant variant enters the country.

Chile’s vaccination campaign has been a highlight in Latin America, as its neighbors struggle to secure their own fires as they are hit by a second wave of infections.

But the country is battling a wave of new infections that have forced the government of President Sebastián Piñera to implement a new blockade, close borders and postpone elections scheduled for this month. New coronavirus cases have risen to more than 9,000 a day this month, the highest total daily, pushing hospitals to capacity with an influx of younger patients.

Health experts say the rise in infections highlights the risk of reduced social restrictions before enough people are inoculated to prevent the virus from spreading and threatening variants such as P.1, first identified in Brazil.

Some epidemiologists say Chile was too quick to celebrate its rapid launch of vaccination. As officials eased restrictions, residents lowered their guard over measures such as wearing masks, washing hands and social distancing, believing the pandemic would end soon, said Claudia Cortés, an infectious disease expert at the University of Chile. .

“They gave the wrong message,” she said. “It was very confusing for the general population.”

Chile 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 single shot and 67% effective two weeks after the second dose.

Officials and doctors say vaccines are starting to work. As cases increase in people under the age of 60, infections begin to decline for high-risk seniors, whose deaths have declined, according to government data. The two-dose regimen is 80 percent effective in preventing death with Covid-19, the government said.

“There is now a clear trend that we can see with the separation of the curves between the 70-year-olds and the younger ones, who are just starting to be vaccinated,” said Miguel O’Ryan, a public health expert at the University of Chile.

UK officials, who are struggling with vaccine supply issues as they chart a route out of a blockage strictly necessary to control the contagious variant B.1.1.7 first detected in England, see Chile’s experience as a story. for warning. The country has suffered the highest number of deaths in Europe, and government scientists and public health experts are calling for the slow and gradual release of restrictions to ensure vaccinations outweigh the virus.

Disease modelers advising the British government have looked at the possible evolution of the pandemic next year, if restrictions on the economy and daily life are eased, according to Prime Minister Boris Johnson’s four-step roadmap, which is not blocked. .

Their work highlights the risk of an exit wave, a model of epidemiologists at Imperial College London suggesting that the UK could handle another five million cases by June 2022 if controls are relaxed as planned. This is more than the four million known cases already registered, although the gaps in the early testing of the pandemic mean that the true total number of infections is probably much higher.

Vaccination means that hospitalizations and deaths caused by Covid-19 are probably much lower than in previous pandemic increases, according to the models. But they are still substantial, the Imperial model, for example, indicates another 15,700 deaths in June 2022. To date, the UK has suffered 150,000 deaths, with Covid-19 mentioned on the death certificate.

A group of scientists advising the government said in a report that the size of any exit wave will be extremely sensitive to issues such as the speed and level of vaccine absorption, any supply hiccups and the still uncertain role that hot weather plays and summer behavior. in limiting the spread of the virus.

Another critical factor is how effective vaccines are at stopping transmission, beyond preventing infection or severe disease.

A vaccine that is extremely effective in stopping transmission would probably mean far fewer cases and very few deaths, said Prof. Medley, who is in the advisory group.

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

and BioNTech SE is extremely effective in preventing further transmission.

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