New York, Dec 4 (IANS): With cases of the Omicron Covid-19 variant reported in several states from New York to Hawaii, US health officials have said that community spread is inevitable, and more vaccinations will play a pivotal role in keeping the virus at bay.

As of Thursday night, the Omicron variant had been detected in at least five US states, namely New York, California, Hawaii, Minnesota and Colorado. At least 10 cases were reported in the country, as some local leaders are warning that the variant has started spreading within some communities.

US President Joe Biden is confronting the worrisome new variant with a strategy that encourages boosters for all adults and aims to expand testing availability and improve its affordability, with the plans laid out in a speech from the National Institutes of Health on Thursday, Xinhua news agency reported.

Also on Thursday, New York Governor Kathy Hochul and Mayor Bill de Blasio pressed New Yorkers not to panic in light of the confirmed Omicron cases, and recommended booster shots for eligible people. They said it was too soon to know how much of a threat the variant might pose to the state.

Takeshi Kasai, the World Health Organisation's western Pacific director, told a media briefing on Thursday that vaccines are the solution while border controls can only buy time, urging countries to fully vaccinate vulnerable groups and stick to preventive measures such as mask wearing and social distancing.

Scientists in South Africa said that Omicron is at least three times more likely to cause reinfection than previous variants such as Beta and Delta, citing statistical analysis of some 2.8 million positive coronavirus samples in this country, 35,670 of which were suspected to be reinfections.

US retail pharmacies are struggling to quickly administer Covid vaccines in some places. "Vaccine seekers in some states face waits of days or weeks for doses as local health officials hustle to improve access to meet surging demand," reported The Wall Street Journal (WSJ) on Friday.

CVS Health Corp. Walgreens Boots Alliance Inc. and Walmart Inc., which are facing staffing shortages, now say they may not be able to accommodate people without appointments.

Millions of Americans are newly eligible for booster shots, and federal health officials in November recommended the vaccine for use in children as young as five years old. Concerns about the risks posed by the new Omicron variant also are driving more people to get vaccinated, health officials were quoted as saying.

The UN was averaging about 1.5 million doses administered a day for a seven-day period as of November 17, a nearly 12 per cent increase from the previous week, according to the Centers for Disease Control and Prevention (CDC).

Many vaccination and booster shot combinations appear to increase people's protection against the coronavirus, but Pfizer's and Moderna's shots -- both based on mRNA technology -- may work best, according to a new study.

"The results lend weight to 'mix-and-match' booster shots, which the US's top public health official endorsed this fall," The Washington Post reported on Friday in evaluation of the study.

The study, published on Thursday in British journal the Lancet, examined people who were initially vaccinated against the coronavirus with either the Oxford-AstraZeneca vaccine or the Pfizer-BioNTech vaccine.

Researchers gave study participants a wide range of booster shots and found that almost all of those vaccines boosted immune responses, regardless of the first set of vaccines received, with Pfizer and Moderna in particular standing out.

Meanwhile, according to WSJ, the US Food and Drug Administration (FDA) is laying the groundwork for the rapid review of Omicron-targeted vaccines and drugs if they turn out to be needed.

The agency, building on rules established earlier this year to assess shots and treatments, has been meeting with drugmakers and setting guidelines for the studies and data needed to swiftly evaluate products targeting the new Omicron Covid variant, said the report.

"The FDA wants to be sure Omicron shots and therapies work safely and can be made correctly before authorising their use, while moving as quickly as it can to conduct the assessment to aid efforts to stay ahead of the variant," it added.