Recovered COVID patients likely protected for at least six months, study finds
KATE KELLAND
By Kate Kelland
LONDON (Reuters) - Almost all people previously infected with COVID-19 have high levels of antibodies for at least six months that are likely to protect them from reinfection with the disease, results of a major UK study showed on Wednesday.
Scientists said the study, which measured levels of previous COVID-19 infection in populations across Britain, as well as how long antibodies persisted in those infected, should provide some reassurance that swift cases of reinfection will be rare.
"The vast majority of people retain detectable antibodies for at least six months after infection with the coronavirus," said Naomi Allen, a professor and chief scientist at the UK Biobank, where the study was carried out.
Video: The latest on peopleĆ¢€™s response to the COVID-19 vaccine
The latest on people’s response to the COVID-19 vaccine
Dr. Jen Ashton shares a study that found people with antibodies had a 10 times stronger antibody response after a single vaccine dose.
Among participants who had tested positive for previous COVID-19 infection, 99% retained antibodies to SARS-CoV-2 for three months, the results showed. After the full six months of follow-up in the study, 88% still had them.
"Although we cannot be certain how this relates to immunity, the results suggest that people may be protected against subsequent infection for at least six months following natural infection," Allen said.
She said the findings were also consistent with results of other studies in the United Kingdom and Iceland which found that antibodies to the coronavirus tended to persist for several months in those who have had the disease and recovered.
A study of UK healthcare workers published last month found that people who have had COVID-19 were likely to be protected for at least five months, but noted that those with antibodies may still be able to carry and spread the virus.
The UK Biobank study also found that the proportion of the UK population with COVID-19 antibodies - a measure known as seroprevalence - rose from 6.6% at the start of the study period in May/June 2020 to 8.8% by November/December 2020.
SARS-CoV-2 seroprevalence was most common in London, at 12.4%, and least common in Scotland at 5.5%, it found.
(Reporting by Kate Kelland; Editing by Alison Williams)
No other nation comes close. In fourth and sixth place, respectively, the United Kingdom (15 doses per 100 residents) and the United States (10 doses per 100 residents) trail far behind.
The main driver of Israel’s rapid rollout — an efficient nationalized health system in which all 9 million citizens hold identity cards and register their electronic medical files with one of the country’s four national health maintenance organizations (HMOs) — is not something other nations can emulate on the fly. And other nations wouldn’t want to emulate Israel’s controversial refusal to vaccinate the vast majority of Palestinians.
An Orthodox Jewish man receives the Pfizer-BioNTech COVID-19 vaccine on Jan. 11 as a part of a nationwide vaccination campaign. (Ilia Yefimovich/dpa via ZUMA Press)
Yet the rest of the world can still learn a lot from what’s happening there. Now that such a huge share of Israelis have been vaccinated, experts are looking at the country’s experience as a kind of real-world, real-time experiment, with far more participants than any clinical trial and unique data that could start to answer some of our most pressing questions about the power of vaccines to curb the pandemic.
Here are four key takeaways from Israel’s latest numbers:
The vaccines look like they’re as effective as promised — even against the U.K. variant
The launch of Israel’s vaccination campaign on Dec. 19 coincided with the start of its third — and largest — wave of infections. Two weeks later, the country reentered its version of strict lockdown, and even today it’s averaging as many cases as it did during the peak of its previous surge in September.
This has caused some confusion. If the Pfizer and Moderna vaccines work so well, onlookers have wondered, then why is Israel’s outbreak still raging? Adding to concerns were comments late last month from the country’s coronavirus czar claiming that a single dose of the Pfizer vaccine appeared “less effective than we had thought,” based on preliminary data. (Israel struck a deal with Pfizer for a stable pipeline of doses in exchange for patient data.)
Of 163,000 Israelis given both doses of the Pfizer vaccine by Maccabi Healthcare Services, the nation’s second largest HMO, just 31 were diagnosed with COVID-19 during their first 10 days of full-strength protection, the Times of Israel reported late last week.
A health worker prepares a dose of the Pfizer-BioNtech COVID-19 vaccine at Clalit Health Services, in a gymnasium in the Israeli city of Petah Tikva, Israel on February 1, 2021. (Jack Guez/AFP via Getty Images)
Maccabi then compared that number to the number of infections over the same period among an equivalent sample of Israelis with similar age and health profiles who hadn’t been vaccinated — and found that members of the control group were 11 times more likely to test positive.
The upshot? According to Maccabi’s calculations, the Pfizer vaccine is 92 percent effective at preventing infection starting seven days after the second dose — a result that’s right in line with Pfizer’s own clinical data. Subsequent waves of real-world data this week have continued to confirm the 92 percent number.
“This is very, very good news,” Anat Ekka Zohar, Maccabi’s top vaccine statistics analysts, told the Times of Israel. “It is the first study in the world that looks at such a large number of fully vaccinated patients.”
And the good news doesn’t stop there. Of the 31 fully vaccinated Maccabi members who did test positive, not a single person needed to be hospitalized. “They have very, very light symptoms,” Ekka Zohar reported. “We are talking about headache and a mild feeling of sickness, and they are almost completely without fever. It’s really a very light illness.”
In other words, full vaccination seems to make any COVID-19 infection that slips past the body’s bolstered defenses even less risky, on an individual level, than the flu. This is an incredible level of protection. Clinical trials have also shown that all five vaccines with public results can prevent deaths and nearly eliminate hospitalizations.
An Israeli woman receives a Pfizer-BioNTech coronavirus vaccine at a COVID-19 vaccination center in Tel Aviv, Israel on Feb. 2, 2021. (Sebastian Scheiner/AP)
What’s more, Israel’s latest surge has been supercharged by the U.K. variant known as B.1.1.7, which is significantly more transmissible than earlier versions of the virus and now accounts for about 70 percent of all cases there — yet the Pfizer vaccine doesn’t seem to be any less effective because of it. Again, clinical trials previously suggested that B.1.1.7 wouldn’t be able to evade the vaccines. But real world data is reassuring.
Israel’s rapid vaccination rollout may finally be starting to reverse its winter surge
It’s one thing for a vaccine to protect an individual person; the data from clinical trials has consistently been very encouraging on that front. But it’s another thing for vaccination to start to protect a population — and turn the tide of a pandemic. No clinical trial can predict when or how that will happen.
“We say with caution, the magic has started,” Segal tweeted Monday.
United Hatzalah emergency service volunteer Tom Eisenman assists Miri Buchbuch, 84, to an ambulance from her home to receive the Pfizer COVID-19 vaccine in Beit Shemesh, Israel on Feb. 2, 2021. The all-volunteer service is transporting elderly and homebound people to vaccine centers. (Maya Alleruzzo/AP)
All real-world data comes with caveats. In Israel’s case, the precise (and likely conflicting) impact of the lockdowns and new strains is hard to quantify, and people who get vaccinated and tested for COVID-19 are not necessarily representative of an entire population.
Still, Segal’s numbers suggest that even as more transmissible variants increase infections across other age groups, a population that is largely vaccinated will start to be immune, so to speak, from that spread.
Which is exactly the sort of shift in the dynamics of the pandemic that everyone is hoping mass vaccination can trigger.
The side effects have been minor
This week, researchers from Israel’s Health Ministry released a report that should also calm the nerves of anyone who’s anxious about the risks of vaccination.
In the world’s most detailed data yet on how the Pfizer vaccine makes people feel, the Health Ministry reported Tuesday that just 6,575 of nearly 2.8 million Israelis sought medical assistance for side effects after their first shot, or less than a quarter of 1 percent. The figure after the second shot, which is said to pack more of a punch, was nearly identical at 0.26 percent (or 3,592 of nearly 1.4 million recipients), suggesting that even more uncomfortable side effects almost never escalated to formal medical complaints.
According to researchers, any symptoms were “similar in frequency and character to symptoms reported after other vaccines given to the population” — both “mild” and “soon [to] pass.”
Health workers of the Maccabi Health vaccination centre administer doses of the Pfizer-BioNtech COVID-19 coronavirus vaccine inside the parking lot of the Givatayim mall in Israel's Mediterranean coastal city of Tel Aviv on January 26, 2021. (Jack Guez/AFP via Getty Images)
Arm pain accounted for 50 percent of first shot complaints and 22 percent of second shot complaints. Some 41 percent of first shot and 73 percent of second shot complainers reported feeling generally unwell.
An average of just 17 patients per million sought hospitalization after the first shot; that number fell to just three patients per million after the second shot.
“People around the world should feel reassured,” Yoav Yehezkeli, a physician and Tel Aviv University public health expert who was not involved in the study, told the Times of Israel.
In the future, demand could be more of an issue than supply
Israel’s vaccination campaign has been moving so quickly, in fact, that health care providers are finding it increasingly difficult to get people to come in and be vaccinated, with the Health Ministry reporting Monday that the country’s daily rate of vaccinations had fallen by nearly half from two weeks earlier, even as eligibility was recently extended to anyone over 35 as well as students aged 16 to 18.
As a result, local providers have discarded thousands of thawed but unused doses and invited younger, technically ineligible residents to get inoculated. Israel is expected to officially open its vaccination campaign to all ages nationwide by next week.
A teenager receives a vaccination against the coronavirus disease (COVID-19), in Tel Aviv, Israel, January 24, 2021. (Ronen Zvulun/Reuters)
It’s a problem that seems utterly alien to Americans who’ve grown accustomed to supply shortages and crashing appointment websites. But the U.S. could eventually find itself in a similar position. Like Israel, the U.S. has already reserved enough doses of various vaccines to immunize its entire population (and then some). And like Israel, where the vaccination rate is much lower among Arabs and ultra-Orthodox citizens than among other groups, vaccine hesitancy may eventually pose a challenge in the U.S., too.
According to a recent CNN poll, 30 percent of U.S. adults say they won’t even “try” to get vaccinated once they’re eligible. That number climbs to 43 percent among 18-to-34-year olds and soars 56 percent among Americans who approve of former President Donald Trump, who spent much of the 2020 election downplaying the virus’s severity.
It remains to be seen how durable this resistance is and what threat it poses to achieving population-wide herd immunity, which experts define as the point when so many people gain protection through either vaccination or prior infection that the virus can no longer easily spread from host to host.
The gold standard, they say, will be getting about 75 percent of Americans (or 240 million people) fully vaccinated. But given that no vaccines have been approved for the 25 percent or so of Americans who are under 16, hitting that 75-percent mark in 2021 would effectively mean vaccinating 100 percent of eligible adults. That’s hard to do when 30 percent of them say they aren’t even willing to try.
Israel’sexperience should serve as a valuable preview of how declining demand might affect vaccine uptake — not to mention how (and whether) the problem can be solved.
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