Opinion | China's covid explosion shows why we need a genomic early warning radar - The Washington Post | By The Perfect Enemy

The U.S. government’s decision to require inbound air passengers from China to show a negative test for the coronavirus starting Jan. 5 might reassure the public, but is probably of limited practical use. It might delay transmission of a new variant, although China is now afflicted mostly with omicron, which is already widespread in the United States and elsewhere. A second decision announced Wednesday by the Centers for Disease Control and Prevention is more significant and underscores the urgent need for genomic viral surveillance.

That second decision was to expand the traveler-based genomic surveillance program, or TGS, which can detect and characterize new variants of the virus that causes covid-19. The program takes nasal swabs, volunteered by travelers at major U.S. international airports, and tests them for the coronavirus. If the coronavirus is detected, the virus genome is sequenced to identify any new variants. The samples are kept anonymous. On Wednesday, the CDC expanded it to Los Angeles and Seattle, for a total of seven airports, covering 500 flights from at least 30 countries, including about 290 weekly flights from China and surrounding areas. About 80,000 travelers participated from November 2021 to December 2022. The program has also begun aircraft lavatory wastewater surveillance. This effort ought to be expanded into a national and eventually global radar system keeping watch for emerging viruses and bacteria.

Even the current, limited sentinel has value, especially at this moment. China is undergoing an explosion of cases after the abrupt lifting of its “zero covid” policy. Its elderly are under-vaccinated, and the population lacks natural immunity to omicron. The danger is that its escalating toll of infections could generate new variants that might be more transmissible or cause more severe disease, and thus become a threat to the entire world. However, because China refuses to be transparent about the cases, deaths and genomics, the only way to detect variants is to be vigilant outside its borders.

When two flights landed in Milan this week from China, Italian health authorities reported that half the passengers tested positive for the coronavirus. Fortunately, subsequent sequencing showed they were infected with omicron, not a new variant. On Thursday, the European Center for Disease Prevention and Control said the variants spreading in China are already circulating in Europe, which has built up both natural and vaccination immunity.

But China is not the only worry. Variants can emerge from anywhere. An aggressive new offspring of omicron, XBB.1.5, is taking hold in New York and the Northeast. CDC models say the XBB variants represent about 40.5 percent of the total infections in the country. According to epidemiologist Katelyn Jetelina, XBB.1.5 appears to be similar to others in terms of being evasive of immune systems; it has more capability to stick to human cells, but in laboratory tests, it is not yet clear that it is more transmissible.

Tighter scrutiny of passengers coming from China is a short-term measure that can buy time. In the longer run, the nation and the world need to build a system of early warning by viral genomic surveillance.

#Coronavirus, #Coverage

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Published on The Perfect Enemy at https://bit.ly/3Z3RyCM.