The US Centres for Disease Control (CDC) has issued a warning to the country about "another avoidable surge" in coronavirus cases. The number of Covid-19 infections in the US grew 5 per cent last week, the first increase in more than two months, Reuters reported, based on analysis of official data. “Taken together, these statistics should serve as a warning sign for the American people,” CDC director Dr Rochelle Walensky said at a press briefing on Monday. She advised people to continue to wear face masks, social distance, avoid crowds and postpone non-essential travel. The White House also recommended that states and private businesses hold off on taking additional reopening measures. "I am worried that if we don't take the right actions now, we will have another avoidable surge just as we are seeing in Europe right now and just as we are so aggressively scaling up vaccinations," Dr Walensky said. The US announced it had marked two consecutive days of vaccinating close to 3 million people on Saturday and Sunday. The CDC says 13.5 per cent of adults have been fully vaccinated, while over 24 per cent have had at least one dose. Meanwhile, there is still concern over the further spread of multiple variants, including "variants of concern"—the Brazil, South Africa and UK variants—that are more transmissible or could evade vaccine protection. Health officials and scientists have said that the UK variant, along with others, <a href="https://www.thenationalnews.com/world/europe/uk-virus-strain-on-track-to-sweep-the-world-and-become-dominant-variant-1.1164482">will become the majority strain</a> in the US sometime this spring. On Friday, the nation's top infectious diseases expert, Dr Anthony Fauci, said the UK variant likely accounts for 30 per cent of infections. The strain has been found to be <a href="https://www.thenationalnews.com/world/the-americas/british-coronavirus-variant-rapidly-spreading-in-us-study-shows-1.1162421">more transmissible</a> and <a href="https://www.thenationalnews.com/uae/health/uk-strain-could-be-up-to-twice-as-deadly-as-other-covid-variants-1.1181756">more deadly</a>. Dr Walensky called the current moment – a race between vaccines and variants – a "fork in the road" for the US. "We are at a critical point in this pandemic – a fork in the road – where we as a country must decide which path we are going to take." Her comments come after a weekend of record travel numbers. The Transport Security Administration reported that it had processed about 1.5 million air passengers on Sunday, March 21. It was the first time the agency had screened that many people since March 2020. Sunday was also the 11th consecutive day where the agency recorded more than 1 million daily air travellers. Miami Beach <a href="https://www.thenationalnews.com/world/the-americas/miami-beach-curfew-aims-to-shut-down-spring-break-partying-1.1189317">moved to enact a night-time curfew</a> after large crowds gathered, with many not wearing masks. The city has put a curfew in place for three weeks. “We’re worried not just for what happens when you are on the aeroplane itself, but what happens when people travel. That is, they go out, they mix with people who are not vaccinated," Dr Walensky said. "So, I would just encourage people and remind people now is not the time to travel.” Not everyone agrees with Dr Walensky's concern about a potential fourth surge in the US. "I don't think we're going to have a fourth wave," former Food and Drug Administration Commissioner Dr Scott Gottlieb told ABC's <i>Face the Nation</i> on Sunday. "I think what we're seeing around the country is parts of the country that are plateauing, and we're seeing upticks in certain parts of the country." Dr Gottlieb cited potential natural immunity as well as the growing number of people who are vaccinated as reasons not to be alarmed over a coming surge. He does share the CDC's concern over variants, particularly the <a href="https://www.thenationalnews.com/world/the-americas/eyes-on-possible-home-grown-us-variant-found-in-new-york-1.1173383">variant in New York City</a>. Local officials recently said the UK variant and the New York variant <a href="https://www.thenationalnews.com/world/the-americas/new-york-city-variant-spread-accelerating-health-officials-say-1.1181932">account for about 51 per cent of the city's cases</a>. The US leads the world in the number of fatalities from Covid-19, with 542,000 deaths. It also leads in coronavirus cases, with close to 30 million infections recorded.