Understanding The Differences Between Infection and Infectious In COVID-19 – Implications For Prevention And The Emergence Of A New Variant
With the varying terminology related to COVID-19, it’s very easy for patients, their families and yes, sometimes even practitioners to get confused about the precise meaning of some terms. One area that can be especially confusing is the difference between having an “infection” and actually being “infectious.”
First of all, even if a person has been exposed to COVID-19, they may not have been infected, meaning their body has been invaded by the virus and is apt to begin replicating and spreading throughout their body. Even if they have been infected, they may not begin showing symptoms, such as fever, cough or shortness of breath, for up to 14 days after exposure.
To further complicate matters, people who may have been exposed and subsequently become infected, may be infectious (capable of spreading the virus to others) even if they are not currently showing any symptoms. Plus, some of those people who are infected and have no symptoms initially, may actually never go on to develop symptoms, but still be infectious!
Close Exposure and Quarantine
The CDC defines exposure as close contact with someone who has COVID-19, which means being within 6 feet of the person who is ill for 15 minutes or more. Close contact is also defined as having had direct physical contact with that person, such as touching them, giving them a hug or sharing eating or drinking utensils. A person is also deemed to have had close contact if the person who was infected sneezed or coughed on them, or otherwise got respiratory droplets on them. Also included as exposed are those people who actually provided care in the home for someone who was ill with COVID-19.
This is why people who have been exposed, or believe they have been exposed to someone who has COVID-19, should, according to Centers for Disease Control (CDC) guidelines, self-quarantine for 14 days to be sure they are not going to develop the illness. Quarantine means someone who may have been exposed to the virus stays away from others. Isolation, on the other hand, means keeping someone who actually has the virus away from others to avoid spreading the illness.
Although the CDC recognizes 14 days as the optimal quarantine period, they also realize that a shorter quarantine, following strict guidelines, may be recommended in some cases to both reduce the burden on the public health system and to make it easier for people to quarantine. Local public health authorities will make these decisions based on conditions in their geographic areas. Public health officials may consider ending the quarantine after ten days if there have been no symptoms or stopping the quarantine after seven days if there has been a negative test on day five or later after exposure.
Emergence of A New Viral Variants and Implications for Vaccines
In addition to confusion around terminology, there now appears to be a new coronavirus strain which is understandably causing quite a bit of concern. The emergence of the new strain, which is known as the B.1.1.7 variant, is not unexpected, as all viruses mutate over time. The B.1.1.7 variant, which was first seen in the Ul.K., is among several new variants which have been recognized globally.
The U.S. Food and Drug Administration (FDA) recently released a clinical alert to laboratories as well as clinicians warning of the emergence of the B.1.1. 7 variant. The alert underscores the importance of recognizing that false negative COVID test results may result if the part of the virus’s genome assessed by a molecular test has undergone a mutation. These false negative results can potentially occur with any emerging SARS-CoV-2 variant, not just the B.1.1.7 strain.
The FDA also cautions that the new B.1.1.7 variant has been associated with an increased risk of transmission, underscoring the urgency of early detection of the variant to reduce the chances of transmission. Although cases involving the new variant have been isolated in the U.S. the CDC states, that although the new variant does not make people sicker, because it is more easily transmitted, cases are likely to rapidly increase in the coming weeks and months.
Of course, the emergence of new variants, such as the B.1.1.7 strain raises concerns over the efficacy of the newly developed vaccines. A study published by the Imperial College of London (but not yet peer reviewed) suggests an alarming 50 percent increase in transmissibility over the more common form of the virus.
A team led by Jesse Bloom, a viral evolutionary biologist with the Fred Hutchinson Cancer Research Center in Seattle, Washington have found evidence that these mutated viruses can dodge recognition by antibodies in those people who have had COVID-19. The researchers are hoping that because vaccines induce such substantial levels of neutralizing antibodies, that the performance of the vaccines will not be substantially affected. Also, the scientists believe that the human T-cell response from the vaccines may not be affected by the variants.