New variant of coronavirus would have a higher transmissibility 28:33
(CNN) -
Passengers traveling to the United States from the United Kingdom must test negative for covid-19 before leaving, the Centers for Disease Control and Prevention (CDC) announced. Thursday night.
Passengers must have a negative PCR or antigen test within 72 hours of boarding their flight from the UK to the US.
They will also need to provide documentation of laboratory results, either in hard copy or electronically.
Airlines are required to confirm the test results before the flight.
Passengers will not be able to board if they refuse to take a test or do not provide documentation.
The order comes in response to a new variant of coronavirus that is said to have originated in the UK and is potentially more transmissible.
Since the discovery of the variant, more than 40 countries have restricted travel from the UK and, in some cases, also from other countries that have documented cases of the covid-19 variant.
LEE: Genetics experts fear that coronavirus vaccines will not work as well against the UK variant
"On March 14, President Trump issued a presidential proclamation to suspend the entry of foreign nationals who visited the UK in the past 14 days," the CDC said in a statement.
“This has reduced air travel to the United States from the United Kingdom by about 90%.
This additional testing requirement will strengthen our protection of the American public to improve their health and safety and ensure responsible international travel, ”he added.
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The agency said the order will be signed on Friday and will take effect on Monday.
Concerns about UK covid-19 variants
Genetics experts have expressed preliminary concerns that COVID-19 vaccines may be less effective against this new variant.
Pfizer and Moderna are testing their vaccines to see if they work against the new variant.
Pfizer and Moderna test their vaccines against a new variant 0:38
The UK variant of the coronavirus has not been identified in genetic sequencing efforts in the United States, the CDC said Tuesday.
But that may be because the surveillance system is not picking up on it.
"It could be in the United States, and we may not have detected it yet," Undersecretary of Health Admiral Brett Giroir said Monday.
Fauci says the percentage of the population that must be vaccinated to achieve herd immunity could be higher
More than a million people in the United States have received the first dose of the covid-19 vaccine in the last 10 days.
But hundreds of millions more will have to be vaccinated to achieve herd immunity and ultimately stop the spread of the virus.
Dr. Anthony Fauci estimated that 70-85% of the population needs to be vaccinated against the new coronavirus to achieve herd immunity.
This is achieved when a sufficiently large portion of the community is immune to the virus and is unlikely to spread.
"This is purely an estimate," Fauci said.
I don't want anyone to go crazy over this.
They are all estimates, "he added.
The top figure in that estimate is higher than in Fauci's previous estimate, who had said that 70-75% of the population would need to be vaccinated.
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Several factors are involved in estimating the percentage of the population that must be vaccinated to achieve herd immunity, including the rate of spread of the virus and the effectiveness of the vaccine.
Fauci, director of the National Institute of Allergy and Infectious Diseases, said his estimate "without any compelling reason."
He explained that he made his latest estimate after considering that a 90% vaccination rate is needed to control the spread of measles.
"I'm extrapolating from measles, which has a vaccine that is 98% effective," Fauci said.
"But (measles is) such an incredibly communicable disease, even more communicable" than the new coronavirus, he explained.
Moderna and Pfizer vaccines are approximately 95% effective against coronavirus.
The BioNTech calculation
BioNTech CEO Ugur Sahin similarly raised his vaccination estimates this week.
On Tuesday, he said the UK variant of the coronavirus may require countries to vaccinate a larger proportion of the population, raising the bar for herd immunity.
"(On) the issue of herd immunity there is always a discussion about 60-70%," Sahin said.
"But if the virus becomes more efficient at infecting people, we may even need a high vaccination rate to ensure that normal life can continue without interruption," he explained.
"But the 60-70% vaccination rate will really change the situation drastically," added Sahin.
"It's not that we don't have to deal with outbreaks if the virus becomes more effective, but it would still provide a more or less normal life."
CNN's Fred Pleitgen and Mary Ilyushina contributed to this report.
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