What is the endgame for SARS-CoV-2, the virus that is causing worldwide devastation?
In a new study, researchers suggest that if it becomes endemic—circulating in the general population—and most people are exposed in childhood, SARS-CoV-2 may join the ranks of mild cold-causing coronaviruses that currently circulate in humans.
The research was conducted by Emory and Penn State scientists.
Their model draws upon studies of the four common cold coronaviruses and SARS-CoV-1.
For those viruses, the term ‘herd immunity’ is incomplete and possibly misleading.
The four common cold-causing coronaviruses have been circulating in humans for a long time and almost everyone is infected at a young age—younger than measles before a vaccine was available.
Natural infection in childhood provides immunity that protects people later in life against severe disease, but it doesn’t prevent periodic reinfection.
In the study, the model predicts that the infection fatality ratio for SARS-CoV-2 may fall below that of seasonal influenza (0.1 percent), once an endemic steady-state is reached.
The team says a safe and effective vaccine against COVID-19 could save hundreds of thousands of lives in the first year or two of vaccine roll-out, but continued mass vaccination may be less critical once SARS-CoV-2 becomes endemic.
Targeted vaccination in vulnerable subpopulations may still save lives.
Another implication is: during the transition to endemicity, that using symptoms only as a surveillance tool to look for infections and curb the virus’ spread will become more difficult.
Thus, widely available testing may become particularly important during vaccine roll-out to protect vulnerable populations.
So far, the available data on SARS-CoV-2 infection in infants and young children suggest that severity is generally mild and mortality is low.
There are exceptions on the individual level, with some experiencing rare complications such as MIS-C (multisystem inflammatory syndrome in children).
In contrast, if SARS-CoV-2 infection in childhood were to become more severe—like MERS-CoV (Middle East respiratory syndrome-related coronavirus) – routine vaccination programs will be still necessary, the researchers say.
One author of the study is Jennie Lavine, Ph.D.
The study is published in Science.
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