For years, global health officials have used billions of drops of an oral vaccine in a remarkably effective campaign aimed at wiping out polio in its last remaining strongholds _ typically, poor, politically unstable corners of the world.
Now, in a surprising twist in the decades-long effort to eradicate the virus, authorities in Jerusalem, New York and London have discovered evidence that polio is spreading there.
The original source of the virus? The oral vaccine itself.
Scientists have long known about this extremely rare phenomenon. That is why some countries have switched to other polio vaccines. But these incidental infections from the oral formula are becoming more glaring as the world inches closer to eradication of the disease and the number of polio cases caused by the wild, or naturally circulating, virus plummets.
Since 2017, there have been 396 cases of polio caused by the wild virus, versus more than 2,600 linked to the oral vaccine, according to figures from the World Health Organization and its partners.
“We are basically replacing the wild virus with the virus in the vaccine, which is now leading to new outbreaks,” said Scott Barrett, a Columbia University professor who has studied polio eradication. “I would assume that countries like the U.K. and the U.S. will be able to stop transmission quite quickly, but we also thought that about monkeypox.”
COVID-19 parallels: polio disaster helped shape vaccine safety in 1950s
The latest incidents represent the first time in several years that vaccine-connected polio virus has turned up in rich countries.
Earlier this year, officials in Israel detected polio in an unvaccinated 3-year-old, who suffered paralysis. Several other children, nearly all of them unvaccinated, were found to have the virus but no symptoms.
In June, British authorities reported finding evidence in sewage that the virus was spreading, though no infections in people were identified. Last week, the government said all children in London ages 1 to 9 would be offered a booster shot.
In the U.S., an unvaccinated young adult suffered paralysis in his legs after being infected with polio, New York officials revealed last month. The virus has also shown up in New York sewers, suggesting it is spreading. But officials said they are not planning a booster campaign because they believe the state’s high vaccination rate should offer enough protection.
Genetic analyses showed that the viruses in the three countries were all “vaccine-derived,” meaning that they were mutated versions of a virus that originated in the oral vaccine.
The oral vaccine at issue has been used since 1988 because it is cheap, easy to administer _ two drops are put directly into children’s mouths _ and better at protecting entire populations where polio is spreading. It contains a weakened form of the live virus.
But it can also cause polio in about two to four children per 2 million doses. (Four doses are required to be fully immunized.) In extremely rare cases, the weakened virus can also sometimes mutate into a more dangerous form and spark outbreaks, especially in places with poor sanitation and low vaccination levels.
These outbreaks typically begin when people who are vaccinated shed live virus from the vaccine in their feces. From there, the virus can spread within the community and, over time, turn into a form that can paralyze people and start new epidemics.
Many countries that eliminated polio switched to injectable vaccines containing a killed virus decades ago to avoid such risks; the Nordic countries and the Netherlands never used the oral vaccine. The ultimate goal is to move the entire world to the shots once wild polio is eradicated, but some scientists argue that the switch should happen sooner.
“We probably could never have gotten on top of polio in the developing world without the (oral polio vaccine), but this is the price we’re now paying,” said Dr. Paul Offit, director of the Vaccine Education Center at the Children’s Hospital of Philadelphia. “The only way we are going to eliminate polio is to eliminate the use of the oral vaccine.”
Aidan O’Leary, director of WHO’s polio department, described the discovery of polio spreading in London and New York as “a major surprise,” saying that officials have been focused on eradicating the disease in Afghanistan and Pakistan, where health workers have been killed for immunizing children and where conflict has made access to some areas impossible.
Canada could test wastewater for polio ‘should that need arise’: Tam
Still, O’Leary said he is confident Israel, Britain and the U.S. will shut down their newly identified outbreaks quickly.
The oral vaccine is credited with dramatically reducing the number of children paralyzed by polio. When the global eradication effort began in 1988, there were about 350,000 cases of wild polio a year. So far this year, there have been 19 cases of wild polio, all in Pakistan, Afghanistan and Mozambique.
In 2020, the number of polio cases linked to the vaccine hit a peak of more than 1,100 spread out across dozens of countries. It has since declined to around 200 this year so far.
Last year, WHO and partners also began using a newer oral polio vaccine, which contains a live but weakened virus that scientists believe is less likely to mutate into a dangerous form. But supplies are limited.
To stop polio in Britain, the U.S. and Israel, what is needed is more vaccination, experts say. That is something Columbia University’s Barrett worries could be challenging in the COVID-19 era.
“What’s different now is a reduction in trust of authorities and the political polarization in countries like the U.S. and the U.K.,” Barrett said. “The presumption that we can quickly get vaccination numbers up quickly may be more challenging now.”
Oyewale Tomori, a virologist who helped direct Nigeria’s effort to eliminate polio, said that in the past, he and colleagues balked at describing outbreaks as “vaccine-derived,” wary it would make people fearful of the vaccine.
“All we can do is explain how the vaccine works and hope that people understand that immunization is the best protection, but it’s complicated,” Tomori said. “In hindsight, maybe it would have been better not to use this vaccine, but at that time, nobody knew it would turn out like this.”
© 2022 The Canadian Press
Hunting for Pi – the next variant after Omicron – in the toilet – Gavi, the Vaccine Alliance
Disease detectives are on the lookout for the next variant of COVID-19 and since the virus is still in such high circulation worldwide the virus is constantly mutating. This means it could be evolving to better evade vaccines and attack our immune systems. Although Omicron was milder than the variants came before it, scientists have warned the next variant – which will probably be called Pi – could be far more deadly.
“A lot of the lineages we are finding make Omicron look pedestrian.”
Sifting through sewage
As SARS-CoV-2 can be shed in faecal matter for weeks after the respiratory symptoms clear, wastewater is an obvious place to look for new variants.
Tracking circulating pathogens has long been an important way of finding early signals of the presence of a disease in a community – it was critical in the eradication of polio in India, for example. Researchers are also using these techniques to track the spread of monkeypox.
An initiative to look for SARS-CoV-2 in Bangalore, India, has provided early warnings of COVID-19 infection spikes, with the researchers able to identify which variants of SARS-CoV-2 are circulating, and in roughly what proportions.
Have you read
For much of this year, virologist Dr Dave O’Connor and colleagues at the University of Wisconsin-Madison have been tracking a heavily mutated version of SARS-CoV-2 that they narrowed down to one particular area of Wisconsin.
Scientists are starting to believe that chronic COVID-19 infections lingering for months in people who may have compromised immune systems are a hotbed of new variants, as the virus has a long time to mutate.
The variant Dr O’Connor’s team is tracking first appeared in sewage collected in January 2022, and though it shares numerous mutations with Omicron, it came from an entirely different part of the SARS-CoV-2 family tree. The team have tracked the lineage to a company of 30 employees and are now trying to determine their next move.
The next Omicron?
Dr Marc Johnson, a virologist at the University of Missouri in Columbia, is working with O’Connor to trace wastewater lineages in Wisconsin. With their colleagues, they are hunting so-called ‘cryptic lineages’, which are viral lineages in wastewater that didn’t match anything in global databases of millions of sequences.
These cryptic lineages were significant in that they often had several mutations in the spike protein that SARS-CoV-2 uses to enter our cells – and which our immune system targets. Dr O’Connor told Nature that such lineages could help forecast macro trends in SARS-CoV-2 evolution, which could in turn help the development of variant-proof vaccines and treatments.
For these virologists, a lot is riding on early detection of the next major COVID-19 variant. “A lot of the lineages we are finding make Omicron look pedestrian,” said Dr Johnson.
Canada has now ended its COVID-19 travel restrictions, mask mandates
OTTAWA — As of this morning, travellers to Canada do not need to show proof of vaccination against COVID-19 — and wearing a mask on planes and trains is now optional, though it is still recommended.
People entering the country are no longer subject to random mandatory tests for the virus, and those who are unvaccinated will not need to isolate upon arrival.
Anyone who entered Canada in the last two weeks and was subject to quarantine or testing is off the hook as of today.
And inbound travellers do not need to fill out the controversial ArriveCan app anymore, although they can still use it to fill out their customs declarations at certain airports.
Federal ministers announced the end of the COVID-19 public health restrictions earlier this week, saying the latest wave of the disease has largely passed and travel-related cases aren’t having a major impact.
But Health Minister Jean-Yves Duclos warned restrictions could be brought back again if they are needed.
This report by The Canadian Press was first published Oct. 1, 2022.
The Canadian Press
What do I need to know about this year's flu shot? – CBC.ca
Experts say it’s almost time to roll up your sleeve for the annual flu shot.
But this year, some pharmacists say people have questions about the influenza vaccine rollout, which will coincide with the rollout of COVID-19 vaccines that target Omicron strains — also known as bivalent vaccines.
Ashley Davidson, a pharmacist and associate owner of Shoppers Drug Mart in St. Albert, Alta., has fielded a lot of questions.
“So many people are asking about flu shots and I think a lot of that conversation comes around how do they time their vaccines and what does that look like?” she told Dr. Brian Goldman, host of CBC’s podcast The Dose.
Here’s what experts have to say about this year’s flu vaccines.
What do we know about the upcoming flu season?
The number of flu cases this year could look a little different than what we’ve seen over the last few years.
“What has changed in the last two years is we had historical lows throughout the pandemic and we’ve now been in the time of uncertainty about when is it going to come back, what is it going to look like,” said Dr. Robyn Harrison, vice-chair of the National Advisory Committee on Immunization (NACI) and infectious disease specialist, on Wednesday during a webinar on seasonal influenza.
An example of what could come is Australia’s recent flu season, which happens before Canada’s because it is in the southern hemisphere.
The country recently had its worst season in years, with data from Australia’s Department of Health and Aged Care showing influenza infections were higher than the five-year average and infections notably spiked, then dropped, earlier than usual.
Canadians also haven’t had much exposure to flu over the last couple of years because of mask mandates and other public health measures introduced during the pandemic, Davidson said.
“One thing that stands out to me this year is that we won’t have masks in schools. So that is going to increase the potential exposure for flu virus for children as well,” she said.
According to experts, influenza is a serious illness. Up until 2019, it is estimated that there are on average 12,000 hospital stays in Canada due to influenza every year, and about 3,500 deaths each year are caused by the flu, Harrison said.
Influenza is very contagious and spreads by respiratory droplets which cause an infection. Symptoms can vary but commonly include fever, sore throat, runny nose, cough, fatigue and muscle aches.
Who is eligible for a flu shot?
Experts say it’s important to get a flu shot each year as vaccine-induced immunity does wane over time.
There are three types of influenza vaccines approved in Canada, according to NACI:
- Inactivated influenza vaccine
- Recombinant influenza vaccines
- Live attenuated influenza vaccine
Anyone six months of age or older who does not have a known negative reaction to the vaccine should get a flu shot every year.
“The reason why children under six months of age are not included in that is because we know that they don’t mount a good immune response to influenza vaccines,” said Dr. Jesse Papenburg, a pediatric infectious disease and medical microbiology specialist, during Wednesday’s webinar. He is also the chair of the NACI influenza working group.
He said the suggested flu shot schedule for children nine and older and adults is one dose of the influenza vaccine at the beginning of flu season.
For kids aged six months to eight years who have yet to receive a flu shot, NACI recommends two doses given at least four weeks apart.
Who shouldn’t get a flu shot?
Papenburg said NACI recommendations for those who shouldn’t get any of the flu shots include:
- People who have had an anaphylactic reaction to any of the vaccine’s components, except for eggs.
- People who have developed Guillain-Barré syndrome (GBS) within six weeks of a previous flu vaccine (unless another cause has been found).
- Infants under six months of age.
NACI’s recommendations on who shouldn’t get the live attenuated influenza vaccine can be found here.
When should I get a flu shot?
Davidson recommends that people get the influenza vaccine as soon as it’s available.
Canada’s flu season typically lasts from mid-October to April or early May, Davidson said.
“I will often remind patients that although you can get your flu shot right away, it does take about two weeks to develop an immune response to that vaccination,” she said.
“It is important to get your shot as soon as you can to ensure that you have coverage through the flu season.”
Can I get a flu shot and a COVID-19 vaccine at the same time?
For most people, the short answer is yes.
For people age five and older, all seasonal influenza vaccines, including the live-attenuated influenza vaccine, may be given at the same time or before or after other vaccines, including COVID-19 vaccines, according to the most recent recommendations from NACI.
“It is important that you’re protected from both viruses throughout the winter,” said Davidson.
Daybreak Kamloops7:15Flu season expected to be more intense this year
However, kids aged six months to five years shouldn’t receive a COVID-19 vaccine and an influenza shot at the same time, according to NACI, which instead recommends those in this age group wait 14 days between COVID-19 shots and other vaccines.
It’s a precautionary approach “to prevent erroneous attribution of adverse events following immunization to one particular vaccine or the other,” reads the committee’s advice.
How effective are flu vaccines this year?
Experts say influenza vaccines have been proven to help prevent influenza, transmission, complications and hospitalizations.
The effectiveness of flu vaccines can vary year-to-year because it all depends on the strains circulating, Davidson and Harrison said.
For the 2004-2005 flu season to 2019-20, Harrison said the effectiveness of influenza vaccines in Canada has varied between around 40 to 70 per cent.
Every year, World Health Organization (WHO) experts make recommendations on which strains of the influenza virus should be targeted by the vaccines.
This year, WHO recommended three influenza strains — one influenza A (H1N1); one influenza A (H3N2) and one influenza B — for inclusion in the trivalent flu shot.
Although the flu vaccine’s effectiveness can vary, both Harrison and Davidson agree that it does offer protection.
“The effectiveness of the vaccine may not be 100 per cent and may not persist beyond a year, but has impact and that’s why it’s recommended,” Harrison said.
Written and produced by Stephanie Dubois
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