Posts Tagged ‘polio’
Vaccines Don’t Mean We’ll See the Last of Covid, Experts Warn
Past immunization campaigns suggest the disease may never be fully eradicated
Why this prediction that the Covid virus will never be eradicated? Because there will always be a large proportion of susceptible population in the community who are Not vaccinated..
By John Lauerman and James Paton. December 20, 2020
In record speed, vaccines are here, and more are on their way.
Less than a year since the coronavirus began ravaging the world, the first shots are raising hopes for wiping the Covid-19 pandemic from the face of the earth.
Today’s programs in the U.S. and the U.K. are precursors to immunization campaigns intended to reach the planet’s entire population — all 8 billion people in every corner of the globe.
Is there reason for optimism?
Vaccines are the best way to eliminate infectious disease: Smallpox has been eradicated and polio is on the brink, with just two countries where transmission persists. (How about the countries succumbing to sanctions from receiving vaccines, basic medication and basic food? Like Yemen, Libya, Syria, Palestinians in Gaza and West Bank…?)
But global vaccine campaigns take time — usually decades — suggesting that even with the latest technologies, money and power behind the unprecedented global drive to knock out Covid-19, the disease is unlikely to be eliminated any time soon.
“I would be surprised to see an actual eradication of this virus now that it’s all over the world, I’d be shocked, given how contagious it is.” said Walter Orenstein, associate director of the Emory Vaccine Center in Atlanta and former head of the U.S. Centers for Disease Control and Prevention’s immunization program. “I’d be shocked, given how contagious it is.”
Snags in supply and distribution have already arisen in the opening days of the U.S. campaign, and the U.K., the first Western country to begin immunizing, vaccinated just 138,000 people in its first week. Meanwhile, Europe has yet to start inoculations, and probably won’t do so until after Christmas.
Concerns are growing over how long it will take to immunize vast swaths of the world beyond a group of wealthy countries that have snapped up early supplies.
A global program called Covax, which aims to deploy Covid vaccines around the globe, has secured deals with developers including Johnson & Johnson and AstraZeneca Plc.
But some of those supplies are expected to come from an experimental inoculation from Sanofi and GlaxoSmithKline Plc that’s been delayed and may not be ready until late next year.
“It’s really, really complicated to make sure we get those vaccines produced and distributed in an equitable way globally, for both moral and economic reasons,” Mark Suzman, chief executive officer of the Bill & Melinda Gates Foundation, told reporters on a Dec. 9 call.
Suzman pointed to research showing that broad access to vaccines could deliver significant economic benefits to all countries and save many lives.
Since wealthy nations will likely have more than enough doses to vaccinate their entire populations, they should consider the reallocation of some supplies to those most in need, he said.
Mass vaccination has been one of the most successful public health interventions in the world and has played an important part raising U.S. life expectancy by more than 50% over the last century.
About a third of U.S. deaths in 1900 occurred in children under age 5, many of them from diseases like smallpox, measles and whooping cough that are now preventable by immunization.
Some new vaccines have also gained quick and widespread use, like shots that prevent pneumococcal infections that can cause severe illness in children and adults. Introduction of the shingles vaccination has offered prevention of the painful disease to millions of people over the past two decades.
A veteran of the World Health Organization effort to eradicate smallpox, Orenstein would often immunize himself in front of entire villages to assuage safety fears.
The agency resolved to try to eradicate the disease in 1959 when it still afflicted many developing countries, but the effort didn’t kick into high gear until 1967 when more funds and personnel were committed by the WHO and its members.
The smallpox effort initially targeted entire populations, but that turned out to be impractical, recalled William Schaffner, a Vanderbilt University infectious-disease specialist who has advised the government on vaccination. The turnaround came when the strategy switched to identifying cases and then vaccinating everyone in proximity, sometimes hundreds of households.
This approach of creating a vaccination ring around cases was only possible, however, because smallpox can be a disfiguring disease, making it easy to identify, and spreads relatively slowly.
“It has this reputation of spreading rapidly but it actually spreads rather slowly,” Schaffner said. “You also need rather close contact for transmission to occur.”
Those features allowed vaccination teams to identify patients just as they were becoming infectious and close off all opportunities for transmission. Even so, it took two decades for the worldwide effort to contain the last outbreak in 1977.
A better comparison to Covid might be polio, an intestinal virus that sometimes causes permanent, severe disease. Polio is similar to Covid in that only a minority of infected people — about one in 100 — become extremely ill.
That’s created one of the problems anticipated in widespread Covid vaccination: People who don’t believe they’re vulnerable to the disease may not want to be vaccinated, even though it may benefit others by keeping hospital intensive-care units free and possibly preventing transmission of the disease.
An important difference with polio, however, is that it can cause severe disease in young children, leaving them with lifelong paralysis, Orenstein said. That’s unlike Covid, which mainly strikes the elderly and chronically ill. That’s left some portions of the public indifferent.
“We’re getting more than a death a minute — on some days two deaths a minute,” he said. “It’s very disturbing to see the lack of concern in other people.”
Yet even with the specter of children paralyzed from polio and a vaccine available for some 65 years, global elimination of that disease still hasn’t been reached.
Two countries, Afghanistan and Pakistan, continue to have spread because of insufficient vaccination rates, according to the Global Polio Eradication Initiative.
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To defeat Covid, “we’ve got to convince people to take the vaccine,” said Anthony Fauci, the top U.S. government infectious-disease specialist, in an interview.
“If you have a highly effective vaccine and only 50% of the people take it, you’re not going to have the impact that you’d need to essentially bring a pandemic down to such a low level that it’s no longer threatening society. And that’s the goal of a vaccine, the same way we did with measles, the same way we did with polio, the same way the world did with smallpox.”
Most standard immunizations provide protection for years to decades. We still don’t know how long Covid vaccines will last, Fauci pointed out.
And it isn’t clear whether they prevent transmission along with protection against symptoms, although studies may soon shed light on that.
The logistics and supply-chain challenge the world faces today is “more complicated than usual because for the first time in history we’ll be introducing multiple vaccines against the same target at the same time,” Rajeev Venkayya, president of Takeda Pharmaceutical Co.’s vaccines business, said in an interview.
That means countries will need databases to track the rollout and ensure people are getting the doses at the right times, as well as systems to monitor potential side effects and share the information with the public, he said.
Early on, countries plan to prioritize the most vulnerable people as well as health-care workers and other critical staff, which will reduce deaths and suffering considerably, said Venkayya, former special assistant for biodefense to U.S. President George W. Bush.
“But transmission won’t go down dramatically in the beginning. It’s going to take time to get to a sufficient level of vaccine-driven population immunity before we begin to dampen transmission.”
Potentially by the middle of next year countries such as the U.K. and U.S. will be able to see a “real dampening of transmission,” he said. “That timeline is going to be delayed in many other parts of the world that don’t have this kind of early access to vaccines.”
Unvaccinated populations always threaten to reintroduce disease into areas where herd immunity appears to have taken over.
Just last year, the annual number of worldwide, reported measles case rose more than six-fold to about 870,000, the most since 1996, as immunization rates flagged.
The world is likely to see the same level of viral persistence from the coronavirus, said Klaus Stohr, a former Novartis AG vaccine executive and WHO official who championed efforts to prepare for pandemics.
“The prediction is pretty clear: The virus will never be eradicated. Why? Because there will always be a large proportion of susceptible population in the community.” said Klaus Stohr
— With assistance by Jason Gale
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