Emerging data suggests that some people who have not been exposed to Sars-Cov-2 have a type of white blood cell (T cell) that recognizes the virus because it has already been exposed to other coronaviruses, such as the common cold. It is not yet known whether these cross-reactive T cells prevent or lessen the impact of infection in people with coronavirus. This is an interesting preliminary finding, but there is currently no evidence that we enjoy collective immunity in the UK.
Studies have consistently shown that less than 20% of the UK population has antibodies to the coronavirus in their blood, and we do not fully understand the mechanisms by which our immune system effectively processes this new virus.
The term collective immunity is ill-defined and unnecessary. This suggests that we can now relax our adherence to measures such as social distancing and facial covers. But this is not the time for complacency. We are heading into a winter that is likely to be difficult, and we all need to continue to do our part to reduce viral transmission. The most likely contributor to the decrease in mortality is the same reason we have seen a reduction in the number of Covid cases: the British population has embraced social distancing, wearing face blankets, working from home and regular hand hygiene.
Are we better at dealing with Covid-19? As much as I would like to say yes, my answer is “not sure”. Many clinical management approaches have been proposed for the coronavirus, such as hydroxychloroquine, ventilation non invasive and vitamin supplements, and a lot to have suggested that given the urgent need for treatments, we should use them as soon as possible. This has led to patients around the world receiving therapies for which there is little evidence of benefit.
During the pandemic, there was immense pressure to bypass our usual avenues of safely discovering treatments. When faced with a devastating disease, the urge to act quickly to find new interventions is not surprising. The controversy surrounding hydroxychloroquine is a good example. Despite mounting evidence that the drug is not effective in treating people who have developed Covid-19, or in preventing the development of the disease in people exposed to the virus, people in countries like the Brazil and the United States continue to receive this treatment. .
There were also many questions about the best way to support people who have difficulty breathing. Many people said their approach was the right one, but there is currently little evidence to suggest that non-invasive ventilation is superior to invasive mechanical ventilation when treating patients with severe cases of Covid-19.
The use of unproven therapies outside of clinical trials should be of concern to us all and has been actively discouraged by Chief Medical Officers in the UK. There is no drug or therapy that does not have side effects or unwanted consequences, so every time we take this approach, patients are at risk in the absence of evidence.Worse yet, every time we administer unproven therapy outside of a clinical trial, we lose an opportunity to learn something that could help save many lives. Evidence suggests that patients enrolled in randomized clinical trials, or who are treated in hospitals with a high level of research activity, achieve better clinical outcomes than those who are not.
There are many therapies for coronaviruses that are currently undergoing rigorous clinical trials. The recovery trial funded by the National Institute for Health Research has recruited more than 12,000 hospital patients with Covid-19 since March and has already provided evidence that anti-inflammatory dexamethasone improves survival in hospitalized patients requiring treatment. oxygen or mechanical ventilation, while the antivirals hydroxychloroquine and lopinavir-ritonavir are ineffective.
We also have evidence from clinical trials in the United States that remdesivir may be an effective antiviral, as well as preliminary data that inhaling interferon-beta-1a may be beneficial, a finding that now needs to be confirmed. in large clinical trials, and recovery- The RS trial seeks to determine how best to support breathing in patients with Covid-19.
During a pandemic, people seek certainty. But science doesn’t work like that. We make assumptions, we test them, we refine them, and we repeat the process. It takes time, and although we are making amazing progress during the coronavirus pandemic, great uncertainty remains. The facts are just things that have not yet been proven wrong, and people who say they know the answers but cannot provide any evidence should be treated with skepticism.
At the moment, we cannot be sure why mortality associated with Covid-19 has fallen in the UK, but many people are struggling to understand why and to lower it even further. In the meantime, we must all continue to do our best to reduce viral transmission while this important work is still in progress.
• Dr Charlotte Summers is Lecturer in Critical Care Medicine at the University of Cambridge