3 things that scientists disagree about coronavirus

Although political leaders have closed borders in response to COVID-19, scientists are working together like never before. But the coronavirus (SARS-COV-2) is new – and we do not have all the facts about it yet. As a result, we may need to change our approach as new scientific data comes in.

That does not mean that science is not reliable – we will get the full picture over time. And there is already great research that can help to inform political decisions. Here are three topics that scientists disagree on.

Face masks

The novel coronavirus spreads by droplets from coughs, niches and speech. To stop the spread of the virus, face masks have become mandatory in many countries.

But there has been much debate among scientists about the effectiveness of face masks on reducing the spread of COVID-19. A report by a multidisciplinary group compiled by the Royal Society has been issued in favor of the public with face masks. These documents, which have not been peer reviewed, claim that face masks can help reduce COVID-19 transmission when used extensively in situations where physical distance is not possible.

One relatively small clinical study also indicated that infected children wearing masks did not pass the virus on to family contacts.

But the science is complex. Face masks will not stop the wearer from ingesting small airborne particles of coronavirus, which can cause infection. A recent study reported that wearing a mask can also give a false sense of security, meaning that wearers may overlook other important measures for infection control.

Research has also shown that when people wear masks, the exhaled air enters the eyes. This generates an impulse to touch the eyes. And if your hands are infected, you can infect yourself. Indeed, WHO warns that masks can become counterproductive unless wearers avoid their face and take other management measures.

We also know that face masks can make us breathe more often and more deeply – possibilities disperse more polluted air.

Many scientists therefore disagree with the Royal Society’s report, and demand more evidence about the effectiveness of masks. Ideally, we need randomized controlled trials involving many people from an entire population to track how masks affect infection numbers.

That said, other scientists suggest that we should use face masks, although completely unreliable evidence is lacking – to be on the safe side. Finally though, without vaccines, the strongest weapons we have are basic preventative measures such as regular hand washing and social distance.

Immunity

Immunologists work hard to determine what immunity to COVID-19 looks like. Many of the studies have focused on “neutralizing antibodies,” produced by so-called B cells, which bind to viral proteins and prevent direct infection.

Studies have found that levels of neutralizing antibodies remain high for a few weeks after infection, but then typically begin to decrease. A peer-reviewed study from China found that infected people had steep declines in antibody levels within two to three months of infection. This has raised doubts about whether people will get longer-term protection against later exposure to the virus. If this study proves correct – the result should be supported by other studies – it may be possible to produce vaccines with long-lasting immunity.

While many scientists believe that antibodies are the key to immunity, others argue that other immune cells called T cells – produced when the body responds to the molecules that fight phytosomes, known as antigens – are also involved. These can be programmed to fight the same as similar viruses in the future. And studies suggest that T cells are at work in many patients fighting COVID-19. People who have never been infected can also hire protective T cells because they are exposed to similar coronaviruses.

A recent study by Karonliska Institute in Sweden, which has not yet been peer reviewed, found that many people who have mild or asymptomatic COVID-19 have T-cell-mediated immunity – even if antibodies cannot be detected. The authors believe that this reinfection can prevent or limit, and estimate that one third of people with asymptomatic COVID-19 could have this type of immunity. But it is not yet clear how it works and how long it will last.

If this is the case, it’s very good news – which means that public immunity to COVID-19 is likely to be higher than antibody tests have suggested. Some have argued that it could create “herd immunity” – causing enough people to become infected to become immune to the virus – with an infection rate as low as 20%, instead of the widely accepted 60-70%. However, this claim is still controversial.

Immune response to COVID-19 is complex, with the whole picture likely to expand beyond antibodies. Larger studies over longer periods now need to be done on both T cells and antibodies to understand how long lasting the immunity is and how these different components of COVID-19 immunity are related.

Number of cases

The reporting of coronavirus cases varies drastically around the world. Some regions report that less than 1% of people are infected, and others that more than half of the population has COVID-19. One peer-reviewed study estimated that only 35% of symptomatic cases were reported in the US, and that the figure was even lower for some other countries.

When it comes to estimating true prevalence, scientists simply use one of two main approaches. They test a sample of people in a population on antibodies and immediately report these figures, as they predict how the virus has affected a population using mathematical models. Such models have given very different estimates.

Research conducted by the University of Toronto in Canada, which has not yet been peer reviewed, reviewed data on blood tests of people around the world and discovered that the proportion that the virus has has varied in different countries.

We do not know why. There could be real differences due to the age, health or distribution of each population – as in virus control policies. But it is very likely that it depends on differences in methodology, such as antibody tests (serological tests): different tests have different sensitivities.

Antibody studies suggest that only 14% of people in the UK had COVID-19, compared to 19% in Sweden and 3% in Yemen. But that excludes T cells. If they provide a reliable handbook for infection, the number may be much higher – potentially close to herd immunity in some regions – but this is hotly debated.

This article was republished from The Conversation by Manal Mohammed, Lecturer, Medical Microbiology, University of Westminster under a Creative Commons license. Read the original article.

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