BY OSAMU TSUKIMORI, STAFF WRITER
New, potentially more infectious variants of the novel coronavirus that surfaced in the U.K. and South Africa have been detected in Japan over the past week, raising alarm that this could further accelerate the spread of the virus and cast a shadow over the economic recovery, let alone the hosting of the Tokyo Games slated for next year.
What do we know about the new variants and what are the overall ramifications, including whether the vaccines are effective against them?
The new variant, originally found in mid-September in the southeast of the U.K., has dozens of mutations including genetic changes in the spike protein that the coronavirus uses to infect human cells.
Medical sources say the new variant, called B.1.1.7, is said to be responsible for some 60% to 70% of new cases in the southeast of England and could be up to 70% more contagious. Another variant found in South Africa, which authorities have said might be the cause of a surge in infections there, has been detected in a woman in her 30s who arrived in Japan earlier this month.
Mutations occur regularly, with thousands of mutations of the new coronavirus having been reported around the world. Scientists calculated how many mutations they expected to occur since the outbreak began about a year ago, using what’s called a molecular clock, on the assumption that the virus undergoes around two mutations per month. But they were perplexed following the revelation that the British variant had significantly more mutations than expected from the original Wuhan strain in China.
“The reason for concern is that these variants are not characterized by one or two mutations, but by many,” said Bill Hanage, associate professor of epidemiology at the Harvard T.H. Chan School of Public Health.
“In the case of the U.K. one (B.1.1.7), around 20 more than we would expect. And there is pretty good evidence from the U.K. in particular that they transmit more readily than the virus we have been facing for the last year,” Hanage said. “The U.K. and South African variants emerged independently from each other, but they share some characteristics including one specific mutation S:N501Y. This is known to increase binding affinity to the receptor the virus uses to enter cells.”
Experts said there is no data to suggest that the antibodies elicited by vaccines would not be effective against it.
According to the European Centre for Disease Prevention and Control, mutations in the new variants relate to the receptor binding site, which may alter the antigenic properties of the virus, and that it is likely that some reduction in neutralization by antibodies will be seen.
Barry Bloom, professor of immunology and infectious diseases at the Harvard T.H. Chan School of Public Health, says that nobody knows whether the new strains of the virus will be able to escape the immune responses generated by the vaccines.
“The virus has relatively little wiggle room to make mutations (that will allow them) to escape antibodies,” Bloom says.
If they mutate too dramatically, Bloom says they would be able to escape antibodies but it would be harder for them to bind to the host cell receptors, which would compromise their ability to get into cells.
But Ken Ishii, professor of vaccine science at the University of Tokyo, warns that the novel coronavirus could outsmart the vaccines sooner or later.
“Theoretically speaking, it may be a matter of time before the virus causes mutations that would evade antibodies of the vaccines in the end,” he said. “Nobody can predict whether that’s five or 10 years from now or next year.”
Ugur Sahin, CEO of Germany’s BioNTech SE, which partnered with U.S. pharmaceutical giant Pfizer Inc. to develop the mRNA vaccine rolled out in Europe and the U.S., has said he believes that the vaccine is effective against the new strain.
If it were not, it could develop a new shot to counter a new variant within six weeks, he said.
If the vaccines are modified to counter a new strain, there would probably be no need to conduct another set of thorough clinical trials like they went through the first time as long as there are no major changes to the vaccine’s production or components, medical sources said.
Back to normalcy
With the rollout of the vaccine in other countries, expectation is rising that life will be back to normal in the not-so-distant future.
Ishii, however, says it will likely take a few years for vaccine coverage to reach the level necessary for effective immunity, and then an additional few years before new infections fall drastically.
“It will take at least four or five years before new coronavirus infections effectively disappear,” he said.
Hanage of Havard University says the results of the simplest models show that society would need to reach vaccine coverage of around 50% to achieve herd immunity, but added that the coronavirus would likely stay around for longer.
“I think it’s extremely unlikely that we would be able to eradicate this virus,” Hanage said. “We have only successfully eradicated one virus, which had a particular set of properties that made it amenable to eradication, and that’s smallpox. We have been struggling with polio for decades.”
More transmissible, lower virulence
With the new strain said to be up to 70% more transmissible, will that mean the novel coronavirus keeps evolving?
“The answer is yes in the sense that the virus is trying to survive by making itself more transmissible,” said Tetsuo Nakayama, a project professor at Kitasato Institute for Life Sciences and director of the Japanese Society of Clinical Virology.
“By becoming more transmissible to humans, virulence tends to become lower because it would do no good if it infects lots of people and kills them. A lot of viruses in general were powerful when they first came out, but as they gradually adapt to humans, they would generally boost their infectivity but lower their pathogenicity. Otherwise they would not be able to survive.”
Hanage agrees, saying the most recent report from the U.K. suggests that B.1.1.7 does not cause a much more severe disease.
“It also suggests that vaccines are likely to remain effective because there are similar numbers of re-infections in each group — indicating that the variant is not evading the immune response. This and other modeling studies suggest that B.1.1.7 is around 50% more transmissible than previously circulating viruses.
“It is not resistant to drugs or medicine.”
He added that the situation for the new variant found in South Africa is less clear and that more data is needed.
Herd immunity in Japan
Japan has a checkered history in which a number of vaccines have been temporarily suspended over the past five decades amid mounting public concerns about side effects, raising concerns that it may take longer for Japan to reach herd immunity.
The Diet passed a revised Immunization Act in early December making the vaccinations free of charge and urging residents to get vaccinated if the shots are proven to be effective and safe.
But the government may have a hard time convincing residents to get vaccinated, as Japan’s confidence in vaccines is among the lowest in the world. In a 2016 EBioMedicine study of 67 countries, 31% of Japanese were skeptical of vaccine safety, ranking the third-highest following France (45.2%) and Bosnia & Herzegovina (38.3%). The global average was 13%.
Ishii says that Japan needs to learn from its failings with vaccines in the past, although no vaccine is generally free from causing side effects in people if 1 million or more people get the shot.
In the past, those rare side effects have often been reported widely on TV and in other media, which has led to people shunning vaccines, he said. He added that given the spread of the pandemic, it would be a correct judgment to think that getting vaccinated is necessary to protect the masses.
“Japan has had multiple cases where a disease that can be prevented by a vaccine has spread,” he said. “I am keenly aware of the responsibility researchers and medical organizations have for a lack of measures trying to prevent this.”
“There should not be any time lag this time.”