What epidemiologists call the ‘exit wave’ and why they recommend not slacking off even as vaccination increases

“Given the low rate of COVID-19 infections as a result of the rapid and effective vaccination plan, the risk of contracting the virus in open areas is very limited.” At this conclusion came the Israeli experts and they determined that the use of masks in open spaces is no longer mandatory in this country, which continues with its gradual de-escalation of restrictions.

In the same line, in the United Kingdom, they ensure that they are “in a kind of race between vaccination and the virus”, and they plan a phased reopening for the next few months.

Between, Chile, with vaccination campaign seen as a model in Latin America, battles wave of new infections this forced the government of President Sebastián Piñera to put in place a new blockade, to close the borders and to postpone the elections scheduled for this month.

Yes In the United States, another country that is progressing with record vaccination figures and is committed to a return to normalcy, the risks associated with the increase in new cases persist, even after having inoculated a large part of its population.

According to epidemiologists, the risk of what they call an “exit wave” is real and is no more and no less than the possibility of new infections as countries lower their guard as vaccines increase.because it is known that vaccines do not offer 100% protection against COVID-19. In addition, there are new variants of the coronavirus that can evade immunity conferred by vaccination.

For specialists, “Relaxing restrictions too quickly may cause the virus to take its chance.”

Yet even with a new wave of infections, Scientists are hopeful that extended vaccination coverage should offer significant protection against serious illness and death. Data from the three countries show that priority risk groups for immunization are mostly disease free.

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

The United States, meanwhile, has given one or more injection to 39% of its population and the 27 members of the European Union have vaccinated only 18% of theirs together, according to published information. The Wall Street Journal.

Experts agree that Israel offers a lesson on what happens if the vaccination surpasses the virusThe country was averaging more than 8,000 new infections a day at the height of its last big wave in mid-January, and new cases are now in the hundreds. In fact, some Israeli hospitals, including the country’s largest, Sheba Medical Center, have started closing their COVID-19 treatment rooms.

And while scenes of crowded restaurants and bars as Israel’s economy reopened in March and students returned to classrooms raised concerns about a possible new wave, cases have continued to decline, suggesting that widespread immunity to vaccination or previous infection is controlling the spread of the virus.

Eren Segal is a computational biologist at the Weizmann Institute in central Israel and said there would be an even lower chance of a resurgence by the summer as the country is expected to have vaccinated large numbers of its 12-15 years old by then. size of the sensitive population. An extensive testing program aims to keep the virus under control in young children. Researchers now say they don’t expect more spikes in infections unless a vaccine-resistant variant enters the country.

Chile’s vaccination campaign is an example to follow in the region, where neighboring countries are struggling to obtain vaccines while being hit by a second wave that does not give a truce.

However, new coronavirus cases topped 9,000 a day this month (the highest daily total since the start of the pandemic), pushing hospitals to capacityeven with an influx of younger patients.

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

Some epidemiologists say Chile quickly celebrated its rapid vaccination. And as authorities relaxed restrictions, people let their guard down on measures such as the use of masks, hand washing and social distancing, believing the pandemic would soon end. “They gave the wrong message; for the general population, it was very confusing “, said Claudia Cortés, expert in infectious diseases at the University of Chile.

Not least the data is that the trans-Andean country based its vaccination campaign largely on China’s Sinovac vaccine, which the Chilean government said last week was only 16% effective in reducing the risk of infection after injection and 67% effective two weeks after. the second dose.

However, Officials and doctors say vaccines are starting to work and if cases increase in people under the age of 60, infections start to decrease in high-risk older people, whose deaths have stabilized, according to official figures. The two-dose regimen is 80% effective in preventing death from COVID-19, the Chilean government said.

“Now there is a clear trend that we can see with the separation of the curves between the over 70s and the older ones, who are just starting to get vaccinated,” said Miguel O’Ryan, public health expert. at the University of Chile. .

UK officials, who grapple with vaccine supply issues as they chart a way out of a strict lockdown needed to control the contagious B.1.1.7 variant first detected in EnglandThey see Chile’s experience as a warning. The country has suffered the highest death toll in Europe, and scientists and public health experts advising the government are pushing for a slow and gradual release of restrictions to ensure vaccines continue to overtake the virus.

Specialists advising the British government analyze the possible evolution of the pandemic over the next year if restrictions on the economy and daily life are relaxed according to Prime Minister Boris Johnson’s four-step roadmap to get out of imprisonment.

Their work contemplates the risk of a wave of exits, with a model for epidemiologists from Imperial College London suggesting the UK could face five million more cases through June 2022 if controls are relaxed as expected. That’s more than the four million known cases already on record, although gaps in testing at the start of the pandemic mean the actual total of infections is likely much higher.

According to models, high vaccination rates and deaths from COVID-19 are likely much lower than in previous waves of the pandemic. But Authorities are closely following the model of Imperial College, which, for example, reports up to 15,700 additional deaths through June 2022.

Experts predict that the size of any release wave is closely related to issues such as the speed and level of vaccine uptake, any supply issues, and the still uncertain role hot weather and summer behavior play in. limiting the spread of the virus. .

Another critical factor is the effectiveness of vaccines in stopping transmission, beyond just preventing serious infections or illnesses.

“A vaccine that is highly effective in stopping transmission would likely mean far fewer cases and very few deaths,” said Graham Medley, professor of infectious disease modeling at the London School of Hygiene and Tropical Medicine.

And so good data on the effect of vaccines on the spread of the virus is still insufficient, studies in Israel and the United Kingdom suggest that the vaccine developed by Pfizer Inc. and BioNTech SE is very effective in preventing progressive transmission.

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