A sign of face mask requirements is seen at a movie theater in New York, the United States, March 5, 2021.(Photo: Xinhua)

The US CDC said on Monday that individuals who are fully inoculated against COVID-19 can gather indoors with unvaccinated people from one other household without wearing masks. The CDC also said if the vaccinated have been around someone who has COVID-19, they do not need to stay away from others or get tested unless they have symptoms.

A Beijing-based immunologist who requested anonymity told the Global Times that the US CDC may be too positive in the impact of vaccines on new infections in the US, which may explain why the CDC released such a guidance. 

The US reported more than 50,000 new cases on Monday. The tally was up from the 40,903 new cases reported on Sunday but still sharply lower than peak levels in January, when daily tallies often exceeded 200,000, Wall Street Journey reported.

But the immunologist believes the downward trend in new infections is not a result of vaccination, but weather. "Warmer weather, however, could reduce infection cases, as the previous epidemic trend in China has shown," he noted. 

He further said that it may be less dangerous to take off masks in summer, but still, it is irresponsible to get vaccinated individuals exposed to COVID-19 patients.

Chinese experts expressed their confusion to the new guidance by the US CDC. 

The impact of vaccines is to reduce the overall infection rate but the protection effect on individuals is still under discussion, Chinese experts said.

The CDC released the advice on its official website, even when it is not exactly sure of how effective the vaccines are against variants of the virus.

The US has administered 92,089,852 doses of COVID-19 vaccines as of Monday morning and delivered 116,378,615 doses, according to the latest data from the US CDC, far from reaching immunity levels.

China' CDC has repeatedly stressed vaccination doesn't mean relaxing of anti-epidemic measures, and people shall continue to wear masks, indoors or outdoors. 

"The protection rate of vaccines is not 100 percent and a few of those vaccinated still get the disease…when an immune barrier has yet to be formed, the novel coronavirus still spreads easily. Vaccinated people should continue to wear masks, especially in public and populated places," China's CDC said. 

The virus mutations are also challenging the US and the further spread of new variants could potentially slow down its downward trend of new infections, said Liang Manchun, associate research fellow at the Institute for Public Safety Research of Tsinghua University. 

The new guidance fits all fully vaccinated people. The US CDC defines those who get their second dose in a 2-dose series, like the Pfizer or Moderna vaccines, or a single-dose vaccine, like Johnson & Johnson's Janssen vaccine, for two weeks as fully vaccinated.