Why even with vaccines, COVID-19 will always be with us - The Detroit News

Posted: 10 May 2021 12:00 AM PDT

Jason Gale, Bloomberg Published 4:31 p.m. ET May 10, 2021 | Updated 4:43 p.m. ET May 10, 2021

The road to eliminating COVID-19 is long and paved with uncertainty. Many countries are counting on vaccines to build sufficient immunity in their populations so that SARS-CoV-2 isn't able to find susceptible people to infect, causing transmission of the coronavirus to slow and eventually stop. But even with the rollout of highly effective vaccines, immunization coverage may not reach that level -- the so-called herd immunity threshold -- anytime soon. For one thing, it's not known what level of immunity is required. There's also the threat of emerging coronavirus variants that may weaken the effectiveness of immunizations.

1. Can COVID-19 be eradicated?

No. So far, only one human disease — smallpox — has been officially eradicated; that is, reduced to zero cases and kept there long-term without continuous intervention measures. Smallpox was stamped out thanks to a highly effective vaccine and the fact that humans are the only mammals that are naturally susceptible to infection with the variola virus that causes the disfiguring, sometimes deadly disease. Humans are the only known reservoir of polio virus, yet it still spreads in a few countries, causing paralyzing disease, despite the widespread use of effective immunizations and a 32-year-old global eradication effort. SARS-CoV-2 is thought to exist in nature in horseshoe bats, and has been known to infect minks, cats, gorillas and other animals. Wiping out the virus would require banishing it from every susceptible species, which isn't feasible. In countries that have successfully suppressed Covid-19 cases, disease elimination has been proposed instead.

2. What's elimination?

It's when efforts to suppress an outbreak have resulted in zero new cases of a disease or infection in a defined area over a sustained period. There's no official definition of how long that should be. One proposal is to make it 28 days, corresponding to twice as long as the outer range of SARS-CoV-2's incubation period — the time between infection and the appearance of symptoms. Some countries, such as New Zealand, have achieved zero new cases for lengthy periods using border closures, lockdowns and diligent case detection and isolation. But as that country has showed, sustaining nationwide elimination of any infectious disease is challenging, if not impossible, because of the threat of the virus re-entering the country from infected travelers.

3. Will vaccines eliminate COVID-19?

It's hard to say. It's not known what proportion of the population needs to have immunity to stop the coronavirus from circulating, or whether even the most potent vaccines will be able to prevent it from spreading. One study estimated that to stop transmission, 55% to 82% of the population would need to have immunity, which can be achieved either by recovering from an infection or through vaccination. However, herd immunity wasn't achieved in Manaus, the capital of Amazonas state in Brazil, even after an estimated 76% of the population had been infected. That's because many people were re-infected with a new variant that evaded virus-halting antibodies generated in response to their initial SARS-CoV-2 infection. Still, there's reason to believe mass inoculations will have a more powerful effect because vaccines appear to elicit stronger, broader and more durable protection than a prior infection.

4. How effective will vaccines be?

There's good real-world evidence from Israel, the U.K., U.S. and Qatar that vaccines will be highly effective at preventing recipients from developing a serious case of covid-19, including from an infection caused by a so-called SARS-CoV-2 variant of concern. Observational analysis in Israel, the first country to report national data on the Pfizer-BioNTech vaccine, showed that two doses provided more than 95% protection against COVID-19 infection, hospitalization, and death, including among the elderly, at a time when the B.1.1.7 variant was the dominant strain. Separately, researchers there found vaccinated individuals who tested positive for SARS-CoV-2 had a lower viral load, probably making them less infectious and less likely to experience severe illness. The quantity of infectious virus people "shed," or emit in respiratory particles, is an indicator of their propensity to spread it.

5. Is that encouraging?

Yes, because the gold standard in vaccinology is to stop infection as well as disease -- providing so-called sterilizing immunity. But it's not always achieved. The measles vaccine, for instance, prevents infection so that vaccinated people don't spread the virus, whereas the vaccine for whooping cough does a good job protecting against serious disease but is less effective at stopping new infections. Encouragingly, early analysis suggests some vaccines will prevent spread. In Israel, the effectiveness of the Pfizer-BioNTech vaccine at preventing asymptomatic infection was estimated at 91.5%, with the protective effect varying from 85.9% in seniors over 65 years to 92.8% in vaccinees ages 16 to 44. Although further studies are needed to determine the extent to which immunization prevents people from developing asymptomatic infections and transmitting the virus to others, the Israeli experience suggests that high vaccine coverage might provide a sustainable path toward resuming normal activity.

6. How do variants of the virus factor in?

The more SARS-CoV-2 circulates, the more opportunity the virus has to mutate in ways that enhance its ability to spread and stick around longer and to evade immunity from natural infection and vaccination. Pressure on the virus to select for variants that can still transmit despite immunity from natural infection or vaccination and cause mild infection will probably be a feature of the pandemic coronavirus in the years ahead, researchers in South Africa said. That will make stopping transmission even more challenging. In recent months, more-infectious variants first reported in the U.K., South Africa and Brazil -- where COVID-19 epidemics have been particularly severe -- have proliferated and spread internationally, causing growing concern. Scientists say the shots should still work at stopping severe disease in the vast majority of cases, but some inoculations may be less effective at protecting against mild infections caused by at least one variant. Researchers have warned that inoculations may need to be updated periodically to maintain their efficacy, and several vaccine makers have begun testing new versions and booster shots.

7. Do COVID-19 vaccines have to prevent infection to curb cases?

No. Vaccines don't have to be perfect to have a public health benefit. New Zealand vaccinologist Helen Petousis-Harris points to rotavirus and chickenpox as examples of diseases that have been "virtually eliminated using vaccines that are very good at preventing severe disease, quite good at preventing any disease, but that do not completely prevent infection in everyone." Since SARS-CoV-2 spreads through respiratory particles from an infected person's throat and nose, a vaccine that reduces the amount of virus in the respiratory tract or how often an infected person coughs may decrease the likelihood of it being transmitted to others and lower the effective reproduction number (Re), which is the average number of new infections estimated to stem from a single case. Mike Ryan, head of the World Health Organization's emergencies program, told reporters Jan. 25 that rather than focusing on eliminating SARS-CoV-2, success should be seen as "reducing the capacity of this virus to kill, to put people in hospital, to destroy our economic and social lives."

8. What if COVID-19 isn't eliminated?

David Heymann, chair of the WHO's Strategic and Technical Advisory Group for Infectious Hazards, warned at the end of 2020 that "it appears the destiny of SARS-CoV-2 is to become endemic." Viruses that are endemic continuously circulate in the community, often causing periodic spikes when disease characteristics and human behavioral patterns favor transmission. Examples include norovirus, the notorious cause of gastroenteritis on cruise ships, and the myriad of viruses, including four coronaviruses, that cause the common cold, especially over the winter.

9. What might the implications be?

People who have survived COVID-19 and those vaccinated against it will probably be protected against the disease for some time. Scientists at the Fred Hutchinson Cancer Research Center in Seattle found blood sera collected from patients who had recovered from a SARS-CoV-2 infection early in the pandemic displayed "generally weak" neutralizing ability against the virus 4-8 months later. But a single immunization with a so-called mRNA vaccine from either Moderna or Pfizer-BioNTech boosted immunological memory, with the concentration of neutralizing antibodies increasing about a thousand fold. Importantly, they found those antibodies appeared potent against the South African variant. It's likely that re-exposure to the virus via a natural infection will also bolster protection. As more and more people develop immunity, the virus will find those who are not yet immune, so long as herd immunity isn't established to protect them. That will mean that people who can't get vaccinated -- because their immune systems are compromised, or they have allergies to vaccine ingredients, or are too young (none of the vaccines authorized in Western countries have been approved for children) -- will remain vulnerable. Some scientists have predicted that, once the endemic phase is reached and primary exposure to the virus is in childhood, SARS-CoV-2 may be no more virulent than the common cold.

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At this point, COVID-19 is a preventable disease -- even as thousands continue to get infected every day - MLive.com

Posted: 24 Apr 2021 12:00 AM PDT

A year ago when Michigan was being ravaged by COVID-19, the big problem was a novel virus that had no vaccine and no effective treatments, and scientists were still trying to figure out exactly how the virus was transmitted.

Today, Michigan is being ravaged in a surge that's even worse than a year ago.

But there's some big difference this time: Vaccines are now available and we know the strategies that best stymie transmission.

"It really is mostly a preventable disease," said Dr. Joel Fishbain, an infectious disease specialist for Beaumont Hospital Grosse Pointe.

So the fact that Michigan emergency departments and COVID-19 inpatient units are overflowing with patients is a huge source of frustration for many health professionals, who say we now have the tools to end the pandemic.

The big missing piece at this point: Widespread public cooperation, both in getting all adults vaccinated as soon as possible and in following mitigation strategies, such as masking and avoiding large gatherings, until that happens.

"The good news is that we have enough science at this point" to know what works, Fishbain said. "I don't want to get involved with the politics of it, but individuals really can prevent the spread of this. ... It is frustrating for us to keep seeing people sick with COVID who have not been vaccinated and certainly could be."

Still, he said, "we're not going to shame people. That's not the way to go about it. It's not about shaming and refusal; it's about individual decision-making. But the more people who get (the vaccine), the better off everybody's going to be."

Vaccinations are key

The most important step that individuals can take: If you haven't already, get vaccinated ASAP.

"The vaccines have been wildly successful" at preventing hospitalizations and deaths, and they also appear to significantly reduce transmission of COVID-19, although more data is needed on the latter, said Dr. Liam Sullivan, infectious disease specialist for Spectrum Health in Grand Rapids.

The vaccines' effectiveness is evident in the huge, dramatic drop in cases in Michigan's nursing homes and prisons, the two hardest-hit settings in 2020.

Michigan's long-term care facilities currently are averaging 15 new COVID-19 cases a day compared to 192 at the height of the fall surge, even as current case numbers are matching fall levels in the general public.

Meanwhile, Michigan's prison system -- where 60% of inmates have agreed to be vaccinated to date -- is now averaging three new cases a day compared to 361 during the first week of December. And the seven-day average positivity rate on coronavirus diagnostic tests has dropped to 0.4% for the corrections system, a stark contrast to the 13.4% statewide average.

Vaccinations serve multiple purposes, doctors say. They not only protect the individual but also the people around him or her. The more people who get vaccinated, the fewer opportunities for the virus to spread. If and when enough people are inoculated, the virus could fizzle out -- which is what happened to once-common diseases such as measles and polio. Vaccines also limit the development and spread of COVID-19 variants.

Fastest path to ending the pandemic? Vaccinations, doctor say.

Sullivan noted there's never been a contagious disease that's been eliminated through natural immunity. He pointed to smallpox and measles as examples, saying there were regular epidemics of both for centuries until mandatory vaccines were implemented for each. (The ability of health officials to mandate vaccines was upheld by the U.S. Supreme Court in a 1905 landmark case, Jacobson vs. Massachusetts.)

"We're not going to achieve herd immunity with COVID-19 by natural infection," Sullivan said. "It's not going to happen. It's a pipe dream and people need to realize that's a pipe dream. The only way we're going to get to herd immunity is through vaccination."

Other mitigation strategies still needed

That said, vaccinations have their limits. While they significantly reduce risk, they don't eliminate it, and Michigan has reported about 400 "break-though" cases of COVID-19 among the 1.8 million residents who are two weeks past their final vaccine dose.

In addition, it takes about five to six weeks from the time that someone gets their first shot of the Pfizer or Moderna vaccine until they are considered fully immunized. For the Johnson & Johnson shot, the process takes about two weeks.

That means less than a fifth of Michigan's population is considered fully immunized now, which is far below herd immunity. That helps explains why Michigan is seeing a current surge in cases even as thousands more people get vaccinated each day.

But coronavirus is largely preventable even for people who are unvaccinated if they follow the protocols strongly advised for the past year -- wearing a mask, social distancing, avoiding large gatherings, especially if they're indoors, Fishbain said.

"Vaccines are a great place to start, but everybody still needs to continue doing the basics -- do not congregate, wear masks, avoid gatherings, etc. etc.," he said.

The science around the value of masking to prevent COVID-19 transmission has gotten stronger over the past year, experts say. And not only does masking reduce the risk of catching coronavirus, but masks also appear to reduce the severity of the disease if an individual is infected, since the person is inhaling less of the virus.

"They're finding out there is direct correlation between viral load and disease severity," Entler said.

That's especially significant now as the B.1.1.7. variant has become much more prevalent in Michigan, and that variant is both more contagious and more lethal.

That variant is a big reason that Michigan's current surge is so problematic. Even as the proportion of coronavirus cases has dropped among senior citizens, thanks to vaccinations, there's been a spike in hospitalizations among younger adults who were much less likely to become severely ill during the first year of the pandemic.

"It's like, you take what we were seeing before and shift it down by one or two decades," Fishbain said. "We've got 20-year-olds who are getting admitted, and 30-year-olds requiring oxygen, which we never saw before, and needing as much treatment as we can give them. We've got 40- and 50-year-olds ending up on ventilators."

Getting public buy-in

Even for people not at risk for serious illness, there are a surprising number who experience "long COVID," where patient's have symptoms that linger for weeks or months.

While most COVID patients under age 50 "don't get severely ill, there are a growing number of people have have long-haul COVID symptoms," Sullivan said. "They have problems with smelling, with taste, with concentration, with memory, with fatigue, with night sweats.

"So even though they had a mild illness the first time around, they're still dealing with these things month and months later, and that's not something you want to deal with when you're 25 or 35," he said. "Of course, you don't want to deal with it at any age, but especially when you're in the prime of your life."

For that reason, prevention is the best strategy when it comes to COVID-19, and that starts with the vaccination, Sullivan said.

And when it comes to weighing potential risks of the vaccines vs. risks of getting COVID, "it's a no-brainer," he said.

The challenge at this point, he said, is "convincing the fence sitters" -- those who aren't opposed to vaccines in general but are hesitant about COVID vaccines because they are so new.

"Probably the best way to get people who are hesitant to get vaccinated is to have their friends and family members who are vaccinated talk to them about it -- talk about why it's important and their own experience with the vaccine," Sullivan said. "I think they're probably in the best position to convince the fence sitters."

Entler said it benefits everybody to get as many people vaccinated as fast as possible.

"I wholeheartedly believe the longer it takes to get enough people vaccinated to get to herd immunity, the longer we're going to be in this pandemic," he said.

Fishbain said that he understands the hesitation about COVID vaccine.

"Is it frustrating? Yes. But do I understand it? Of course," he said. "Have we ever produced the vaccine in six months and released it to the public? No. Have we ever used a messenger RNA vaccine for vaccination? No. Do we have a history of releasing vaccines too early with complications? Yes."

That said, "if you don't get vaccinated, realize that you're highly susceptible to catching the virus, which means you need to do what you're supposed to do to protect yourself from getting infected" -- such as masking and avoiding large gatherings, he said.

Fishbain said he's frustrated by people who refuse to take precautions such as masking but also refuse to be vaccinated.

"You can't have it both ways," he said. "Obviously, we have our individual freedoms and we have our autonomy where we get to make our own choices. But try to make the right choices."

More on MLive:

One public Michigan university is requiring COVID-19 vaccination for students. Will others do the same?

Michigan high schools look to build on lessons as prep sports enter widespread testing for spring

What to do, and not do, with your COVID-19 vaccine card

Delayed care and surge in coronavirus cases overwhelms Michigan hospitals for a third round