Israel, on the verge of obtaining collective immunity?

With a population of just over 9 million inhabitants in a territory of 22,145 square kilometers, already Some voices are encouraged to say that Israel may be on the verge of obtaining collective immunity from COVID-19.

The coronavirus pandemic, which has caused more than 137 million infections and 2.96 million deaths worldwide, According to the Johns Hopkins University & Medicine Coronavirus Resource Center data monitor, it seems to have found a drag in this small Middle Eastern country.

With 863,521 infected and 6,312 dead since the virus began circulating, Israel is making vigorous progress with its vaccination plan. The country started immunizing its citizens in December 2020 and is currently the world leader in terms of implementation.

According to the latest data from Our World in Data, updated April 13, 61.64% have already received the first dose of Pfizer-BioNTech vaccine and 57.25% have already received both requests.

Immunity collective or herd, as it is commonly called, is the indirect protection against an infectious disease that occurs when a population is immune, either due to the effect of vaccination, or due to the immunity developed by a previous infection. In this case, it happens when a sufficient number of inhabitants are protected against an infection which can no longer spread, and even people who do not have immunity are indirectly protected.

The percentage of people who must be immunized to achieve herd immunity varies with each disease, according to the World Health Organization (WHO). For example, herd immunity to measles requires that about 95% of the population be vaccinated and the remaining 5% will be protected by the fact that the disease does not spread among those vaccinated. For polio, the threshold is around 80%.

If the proportion of the population that must be vaccinated against COVID-19 to talk about herd immunity is still unknown, they observe from the WHO, different estimates speak, at least, between 65% and 70%.

With more than half of the population vaccinated, in addition to people who, due to being infected with the coronavirus, have generated natural immunity, It is estimated that around 68% of people in Israel already have antibodies in their blood that can fight the virus and this leads specialists to wonder if they may be close to achieving the goal..

Professor Eyal leshem, director of the Center for Travel Medicine and Tropical Diseases at Sheba Medical Center, recently said herd immunity was the< seule explication >> as cases continued to decline even as many of the country’s restrictions were lifted.

“We are seeing a decrease in the number of cases, despite the return to mass gatherings and schools after the third shutdown, as most of the people the infected person will meet are immune,” Leshem told US magazine Israel21c.

“This tells us that even if a person is infected, most of the people they pass while walking around will not catch it,” he added.

In Israel, the contagion curve is decreasing in all age groups, including children. Without going any further, the professor It was Segal, the computational biologist from the Weizmann Institute of Sciences., recently said in an interview with a television station in Israel that cases of contagion are down 97% since January thanks to a successful vaccination campaign.

For Leshem, the real challenge is the children and adults who are not vaccinated, as the inoculants have only been given to people over 16 years of age. Vaccines aged 12 to 15 will start in a few months in Israel, following Pfizer’s clinical studies in this population.

“There are no magic tricks here,” Leshem said. “If unvaccinated people travel without a full quarantine and testing, we will increase the risk of the disease being reintroduced to Israel», He clarified.

Some specialists are more careful when talking about a possible collective immunity. Sarah Pitt, a virologist at the University of Brighton in England, called for “extreme caution” as she believes achieving herd immunity will be difficult even with high vaccination rates. “We have to see if the cases in Israel continue to drop and stay low,” he warned.

This look matches that of the young independent data scientist, the American Youyang Gu, who changed the name of its popular COVID-19 prediction model from “Path to Herd Immunity” to “Path to Normalcy”. He said it seemed unlikely to reach a herd immunity threshold due to factors such as vaccination in vaccines, the emergence of new variants and the delay in the arrival of vaccines for children, a stated an article published in the scientific journal Nature.

“Nos estamos alejando de la idea de que alcanzaremos el umbral de inmunidad colectiva y luego la pandemia desaparecerá para siempre”, sostuvo en esa misma dirección la epidemióloga Lauren Ancel Meyers, directora ejecutiva del Consorcio de Modelado COVID-19, Texas de la Universidad de Modelado COVID-19, in the USA.

This change reflects the complexities and challenges of the pandemic, but should not obscure the fact that vaccination is important and useful.. “The vaccine will mean the virus will start to dissipate on its own,” Meyers added. But, as new variants emerge and immunity to infections potentially wanes, “we could find ourselves months or a year later battling the threat and dealing with future waves.”

How does collective immunity work?

It is estimated that, without restrictions, a person infected with the original strain of the virus that causes COVID-19 will infect, on average, about three people. Once two-thirds of the population becomes immune to the virus, an infected person, on average, will only pass it on to another person. This is enough for the virus to spread, but not for it to grow, having removed two of those three people from the chain of transmission.

Achieving this level of immunity in the population is important to protect people who cannot be vaccinated or whose immune system is too weak to produce an adequate protective response.

However, one fact must be taken into account: although vaccines are effective in preventing severe or complex cases, they don’t prevent people from getting sick or block infections at all. This means that some vaccinated people could still transmit the virus.

Additionally, not all people who have been infected with COVID-19 and have recovered have strong or long-lasting natural immunity, and newer variants of the virus are more transmissible.

“We should not look for collective immunity as a sign that we can lift all public health measures and get back to ‘normal’. Very good we should be looking for consistently low levels of COVID-19 infectionPitt pointed out.

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