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The Centers for Disease Control and Prevention (CDC) and the World Health Organization (WHO) have established new criteria for classifying variants of SARS-CoV-2, the virus that causes COVID-19.
The criteria are intended to clarify how much is known about recent changes in circulating viruses. Levels also help convey risks.
The new designations are “variant of interest”; “variant of concern”; and “high-consequence variant.”
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A variant of interest has caused discrete groups of infections in the United States or other countries, or appears to be causing an increase in cases. He also has genetic changes that suggest he may be more contagious or that may help him escape the immunity conferred by natural infection or vaccination. Therapeutic tests and trials may not work so well against. The CDC is seeing three of them.
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A variant of concern it has been shown through scientific research that it is more contagious or that it causes more serious diseases. It can also reduce the effectiveness of therapies and vaccines. People who have previously had COVID-19 can be reinfected by the new strain. The CDC monitors it.
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A high consequence variant it causes more serious illnesses and a greater number of hospitalizations. It has also been shown to defeat medical countermeasures, such as vaccines, antiviral drugs, and monoclonal antibodies. To date, none of the variants meets this definition.
Following the new criteria, the CDC said it was launching a broad network to designate variants of interest, but that it would require stronger evidence before naming a variant of concern.
“CDC is aligned with the WHO approach, as the threshold for designating a variant of interest should be relatively low to control potentially important variants; variants with the highest public health implications,” according to a CDC spokesman.
Previously, CDC classified variants, but is about to change slightly. In the future, final decisions on which variants are important to consider will be made by the CDC in consultation with the new SARS interagency group on variants, which is made up of experts from the National Institutes of Health (NIH), the Food and Drug Administration. , the Department of Defense, the Biomedical Authority for Advanced Research and Development, and the Department of Agriculture.
The working group is urgent, said Michael Diamond, MD, PhD, associate director of the Center for Human Immunology and Immunotherapy Programs at the University of Washington School of Medicine in St. Louis. Louis.
According to scientists familiar with the effort, CDCs have been affected in recent years by budget cuts and political interference, and currently lack the muscle to respond as quickly or as solidly as necessary.
“There has to be some superstructure to deal with this,” said Diamond, who is involved in the effort through an NIH working group. Diamond said between 50 and 100 scientists have joined some of the calls in which he has participated.
“We need to do this because we need to be able to coordinate surveillance with in vitro tests, with animal-based testing with the industry to be able to access their therapeutics, their vaccines and to be able to provide feedback and re-test them over time. This cannot be done just through ad hoc academic collaboration or even an agency, ”he said.
“Let’s say the CDC says,‘ We identified a variant that is emerging in Iowa at high frequency. Well, CDC doesn’t have the facilities to test quickly and quickly whether this variant is really significant or not, “Diamond said.
“So we have to find out. This should start a series of experiments that could be done through academic, governmental and non-governmental agencies, through which we could test this variant, generate recombinant pseudoviruses, generate recombinant viruses and generate recombinant ear proteins, ”Diamond said.
Animal experiments would help assess whether infection rates increase or the effect of vaccines or medications decreases. If it does, decisions would be made about “how will we respond in the context of modifying existing drugs, therapeutics, or vaccines?” Diamond said.
The government would then coordinate with pharmaceutical companies.
Monitoring of emerging variants
Beyond the new CDC / WHO designations, Public Health England, the UK’s counterpart at CDC, uses an additional classification for “investigated variants.” The variants investigated have just been identified and are the subject of ongoing studies, but scientists still know nothing about their importance to public health.
On Tuesday, Public Health England announced it was investigating the emerging variant of P3, which was first detected in the Philippines.
On Monday, researchers in Colombia released a prepress study describing a new variant of B.1.111 with mutations in its peak protein at L249S and E484K. These two mutations have helped other viruses escape the antibodies created by the body in response to both vaccines and natural infection.
Public Health France also announced on Tuesday a new group of cases related to a hospital in the Brittany region caused by a new variant in clade 20C. The French variant has nine mutations in its spike protein and was not detected by PCR tests, suggesting that the changes prevent them from being detected by these tests.
Keep the variants in perspective
When a virus mutates or acquires a change in its genetic code, a variant is created. It is just a different version of the virus from the virus that created it. Variants appear frequently and are not usually harmful to humans. From time to time, a change or group of changes will help a version of the virus outperform other variants. It can reproduce more quickly, for example, or develop a different or more efficient way to infect cells. Sometimes a change will adjust its structure enough so that the antibodies that our immune system produces cannot adhere to it.
When this happens, more illnesses and more serious illnesses can occur. Pharmaceutical companies may need to modify drugs and vaccines to stay up to date.
Variants of concern
To date, CDC is tracking five worrying variants: variant B.1.1.7, first identified in the UK; variant P.1, first detected in Japan and Brazil; variant B.1.351, first published in South Africa; and variants B.1.427 and B.1.429, which have been extended to California.
Currently, surveillance of these variants is limited. The United States does relatively little genomic surveillance of the virus compared to other countries, such as the United Kingdom.
Variant B.1.1.7 is at least 50% more contagious than previous versions of the virus. It has caused significant increases in COVID-19 in the UK, Israel and Europe. As of March 16, the CDC claims that 4,686 cases have been detected in the United States and covers all 50 states.
Laboratories have detected 142 cases of variant B.1.351. These come from 25 states. There have been at least 27 cases of variant P.1 in at least 12 states. Studies have shown that current vaccines are less effective against these two variants. Nor are they as vulnerable to some of the monoclonal antibody therapies that have been developed. Like B.1.1.7, B.1.351 appears to be 50% more contagious.
Variants B.1.427 and B.1.429 appear to be 20% more contagious than previous versions of the virus. They can also slightly reduce the effectiveness of vaccines and therapeutic products. Immunity generated by vaccines is so strong, however, that this reduction is not expected to prevent them from being effective in preventing infections or reducing virus transmission.
Sources
Michael Diamond, MD, PhD, Associate Director, Center for Human Immunology and Immunotherapy Programs, University of Washington School of Medicine, St. Louis, Missouri
CDC variants, SARS-CoV2, updated March 16, 2021
WHO, Weekly Epidemiological Report, 25 February 2021
WHO, Weekly Epidemiological Report, March 16, 2021
Public Health England, Variants of Concern or Under Investigation, updated March 15, 2021
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