A Covid-19 lesson for US from three countries with fast vaccination

Epidemiologists say the risk actually lies in a so-called exit wave of new infections, as countries drop their hats while shots increase, as vaccines do not offer 100% protection against Covid-19 infection. New variants of the coronavirus that can evade the immunity conferred by vaccination or infection in the past increase the risk of a new surge.

Ease restrictions too fast and the virus will take its chances, scientists say.

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

Yet, 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 risk groups who prefer vaccination mostly remain disease-free.

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

The US gave 39% of its population one shot or more and the 27 members of the European Union together vaccinated only 18% of them.

Israel offers a lesson in what happens if vaccination exceeds the virus. The country averaged more than 8,000 new infections a day at the height of its last major wave in mid-January. New business is now in the low hundreds. Some Israeli hospitals, including the country’s largest, Sheba Medical Center, have begun closing their Covid-19 treatment rooms.

Residents packed into restaurants in pubs when the Israeli economy reopened in March and students returned to classrooms.

Instead, cases have continued to decline, suggesting that the widespread immunity to vaccination or infection in the past holds a lid on the spread of the virus.

“Many people, including us, have said that there is a possibility that we will have another wave in March,” said Eren Segal, a computer biologist at the Weizmann Institute in Central Israel and a member of ” a civic advisory committee told the government. coronavirus issues. “We are very happy that this has not happened so far.”

Prof. Segal said that by the summer, the chances of a revival will be even smaller, as Israel is expected to have vaccinated many of its 12- to 15-year-olds by that time, further reducing the vulnerable population. An extensive testing program is aimed at keeping the virus under control among younger children. Researchers now say they will no longer contract 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 secure their own shots while being hit by a second wave of infections.

But the country is struggling with a resurgence of new infections that have forced the government of President Sebastián Piñera to apply a new lock, close the borders and postpone elections scheduled for this month. New cases of coronavirus have risen to above 9,000 a day this month, the highest daily total, pushing hospitals to their capacity with an influx of younger patients.

Health experts say the increase in infections underscores the risk of social restrictions being mitigated before enough people are vaccinated to prevent the virus from spreading, and the threat of variants such as P.1, which were first identified in Brazil.

Some epidemiologists say Chile was too fast to celebrate its rapid vaccination. While officials eased restrictions, residents weakened their hats over measures such as wearing masks, hand washing and social distance, believing the pandemic would soon be over, said Claudia Cortés, an infectious disease expert at the University of Chile said.

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

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

Officials and doctors say the vaccines are starting to produce results. While cases among people under 60 are increasing, infections are starting to decline for high-risk seniors, whose deaths have leveled off, according to government data. The two doses are 80% effective in preventing the death of Covid-19, the government said.

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

British officials, who are struggling with vaccine supply problems as they require a strict exclusion route to control the contagious B.1.1.7 variant first detected in England, consider Chile’s experience as a warning. The country has suffered the highest death toll in Europe, and government health scientists and experts are calling for a slow and gradual release of restrictions to ensure vaccinations surpass the virus.

Disease modelers advising the British government next year analyzed the possible course of the pandemic if the restrictions on the economy and daily life are eased in line with Prime Minister Boris Johnson’s four-step roadmap outside the lock.

Their work highlights the risk of an exit wave, with one model by epidemiologists at Imperial College London suggesting that the UK could face another five million cases by June 2022 if control is weakened as planned . This is more than the four million known cases already recorded, although the gaps in the test early in the pandemic mean that the total number of infections is likely to be much higher.

Vaccination means that hospitalizations and deaths due to Covid-19 according to the models are likely to be much lower than in previous increases of the pandemic. But they are still significant, for example by the model of Imperial, and indicate as many as 15,700 deaths up to and including June 2022. So far, the UK has suffered 150,000 deaths with Covid-19 listed on the death certificate.

A panel of scientists advising the government said in a report that the size of any output wave would be very sensitive to issues, including the speed and level of vaccine uptake, any supply hiccups and the still uncertain role that hot weather and summer behavior play. to limit the spread of the virus.

Another critical factor is how effective the vaccines are in the transmission, in addition to preventing infection or serious illness.

A vaccine that is very effective in stopping transmission is likely to mean far fewer cases and very few deaths, said prof. Medley, who sits on the advisory panel, said.

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

and BioNTech SE are very effective in reversing the transfer.

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