New York, Jan 5 : Many hospitals across several US states have brought back the mask mandates, even as the country is seeing a fresh wave of Covid-19 cases, driven by the highly transmissible JN.1 variant, as well as flu. The Centers for Disease Control and Prevention (CDC) in its latest update before Christmas stated that JN.1 has become the dominant variant in the US. The proportion of JN.1 viruses over the past 2 weeks was up sharply, rising from 15-29 per cent to 39-50 per cent, the CDC said in an update on December 22. The CDC said it is also seeing an increasing share of infections caused by JN.1 in travellers, wastewater, and most world regions. This prompted local officials in several states including New York, Illinois, California, North Carolina and Massachusetts to ask staff, patients and visitors to mask up. Officials at Los Angeles County and New York City ordered all staff and visitors at healthcare facilities to mask up, according to ABC 7. The mandate applies to anyone entering New York H+H hospitals, community health centers and nursing homes, the NYC public hospital system said in statement 'As we've seen an increase in Covid, flu and RSV, this is really to protect our patients, staff and the community,' said Christopher Miller, spokesman for NYC Health + Hospitals 'What we don't want is staffing shortages, right? When we saw the Omicron wave in 2022, the biggest issues were not only people getting sick, but that we had a lot of frontline health workers, they were out with Covid,'New York City Health Commissioner Dr. Ashwin Vasan was quoted as saying to WABC TV. Vasan noted that mask mandates had resumed at all 11 of the city's public hospitals, 30 health centres and five long-term care facilities. Rush University medical system in Chicago said on Tuesday that it was requiring "patients, visitors and staff to wear hospital-approved masks in some areas of the campus. They include clinical waiting areas and patient registration." Mask mandates will also protect patients from other respiratory diseases, like the flu and RSV, that are on the rise this winter. JN.1, classified as a variant of interest (VOI) by the World Health Organization (WHO) due to its rapid spread, is currently present in about 41 countries. It was first detected in Luxembourg in August. JN.1 is similar to its parent BA.2.86, but has an additional mutation (L455S) in the spike protein, which has immune-evasion properties. The CDC said that JN.1's continued growth suggests that the variant is either more transmissible or better at evading our immune systems than other circulating variants. However, it added that 'it is too early to know whether or to what extent JN.1 will cause an increase in infections or hospitalisations'. JN.1 is also becoming the dominant variant globally, causing spikes in infections, hospitalisations as well as deaths in some countries. As per the CDC, existing vaccines, tests, and treatments work against JN.1. /IANS