The World Health Organization’s top emergencies expert Mike Ryans told a briefing on Friday that even if antibodies were effective there was little sign that large numbers of people had developed them and were beginning to offer so-called “herd immunity” to the broader population.
Senior WHO epidemiologists warned despite the hopes governments across the world have piled on antibody tests, there is no proof those who have been infected cannot be infected again.
Speaking at a press conference in Geneva, Dr Maria van Kerkhove said: ‘There are a lot of countries that are suggesting using rapid diagnostic serological tests to be able to capture what they think will be a measure of immunity. ‘Right now, we have no evidence that the use of a serological test can show that an individual has immunity or is protected from reinfection.’ She added: ‘These antibody tests will be able to measure that level of seroprevalence – that level of antibodies but that does not mean that somebody with antibodies means that they are immune.’
The World Health Organization is also not sure whether the presence of antibodies in blood gives full protection against reinfection with the new coronavirus.
World Health Organization epidemiologist Maria van Kerkhove also said at the briefing that a sharp upward revision in China’s coronavirus death toll on Friday was “an attempt to leave no case undocumented.”
Kerkhove said the Chinese authorities had gone back over data from funeral services, care homes, fever clinics, hospitals and detention centers, as well as the number of patients who had died at home, in the city of Wuhan, source of the coronavirus outbreak.
Even as virologists zero in on the virus that causes COVID-19, a very basic question remains unanswered: do those who recover from the disease have immunity?
There is no clear answer to this question, experts say, even if many have assumed that contracting the potentially deadly disease confers immunity, at least for a while.
But for RNA-based viruses such as Sars-Cov-2 — the scientific name for the bug that causes the COVID-19 disease — it takes about three weeks to build up a sufficient quantity of antibodies, and even then they may provide protection for only a few months, Vivier told AFP.
At least that is the theory. In reality, the new coronavirus has thrown up one surprise after another, to the point where virologists and epidemiologists are sure of very little.
“We do not have the answers to that — it’s an unknown,” Michael Ryan, executive director of the World Health Organization’s Emergencies Programme said in a press conference this week when asked how long a recovered COVID-19 patient would have immunity.
“We would expect that to be a reasonable period of protection, but it is very difficult to say with a new virus — we can only extrapolate from other coronaviruses, and even that data is quite limited.”
Since the coronavirus pandemic began, the term “herd immunity” has been flung around as one solution to the devastating virus ravaging countries all over the globe since December 2019. The term explains the situation in which a high percentage of people in a given community (a city, state or entire country) is immune to a disease, either through vaccination or because those people have been exposed to the virus and their immune systems have built antibodies to protect them from it. People who tout it as the best defense against SARS-CoV-2, the virus that causes COVID-19, are correct in their thinking — it’s the best way to prevent contagious diseases from circulating throughout a population because it slows down or eliminates the spread of the virus from person to person.
Experts estimate that from 60% to upwards of 90% of a population must have immunity to a disease for it to stop spreading. Most countries affected by COVID-19 have not surpassed the 1% mark, including the US, which currently has the highest number of cases out of all countries.
The problem with herd immunity and the novel coronavirus is that the world is nowhere close to having widespread resistance to COVID-19, and is still a long way from developing it.
Experts estimate that from 60% to upwards of 90% of a population must have immunity to a disease for it to stop spreading. Most countries affected by COVID-19 have not surpassed the 1% mark, including the US, which currently has the highest number of cases out of all countries.
If there is no herd immunity, people will continue to contract diseases and spread diseases, and, unfortunately, people will continue to die from these diseases. The CDC defines herd immunity, or community immunity, as “a situation in which a sufficient proportion of a population is immune to an infectious disease (through vaccination and/or prior illness) to make its spread from person to person unlikely.
“Even individuals not vaccinated (such as newborns and those with chronic illnesses),” the CDC continues, “are offered some protection because the disease has little opportunity to spread within the community.”
Reuters / Mail / CNET / France 24
