When Dr. Frank Rosenblat treats a hospitalized patient for COVID-19, he breathes a sigh of relief if the person is fully vaccinated.
That’s because antibodies generated by the COVID vaccine likely got a head start on fighting the infection even before treatment begins, said Rosenblat, an infectious disease specialist for McLaren Health in Oakland County.
“If someone says they’re vaccinated, that cuts down the anxiety that they won’t do well,” Rosenblat said. “It cuts it down tremendously. .... They might be ill enough to be in the hospital, but they should be able to get through it.”
Even compared to other cutting-edge treatments such as monoclonal antibodies and remdesivir, “the vaccine is much, much better, much more effective” at preventing the most serious complications from COVID, he said.
As public concern rises about the growing number of breakthrough cases in people fully vaccinated against COVID, Rosenblat and other experts suggest those worries are overblown – at least for now.
In fact, COVID vaccines are working well and easily remain the most effective tool in fighting the COVID-19 pandemic, they said.
Between Aug. 9 and Sept. 8, 25% of the newly confirmed COVID-19 cases were people who were fully vaccinated, as were 25% of those hospitalized with COVID and 19% of the COVID-19 deaths, when compared with all COVID cases.
The latest numbers on breakthrough cases are “definitely a little higher than we expected,” Rosenblat said. But “there’s a lot of nuances in the numbers” that get ignored by the general public, and can lead to misinterpretation and misinformation, he said.
“People need to calm down about the breakthrough cases,” agreed Dr. Liam Sullivan, infectious disease specialist for Spectrum Health in Grand Rapids.
“My take-home message is that people shouldn’t get overly concerned about the breakthrough cases,” Sullivan said. “The vast majority are not requiring hospitalization, and the people who do end up in the hospital aren’t ending up on ventilators and they do go home.
“That’s unlike cases among unvaccinated people, where you see more severe disease and a lot of them end up with permanent health problems,” he said.
To date, 0.5% of fully vaccinated Michiganders have had a breakthrough case, 0.2% have been hospitalized and 0.007% have died (when compared to those who have been vaccinated).
By comparison, among unvaccinated Michiganders, 8.2% have had COVID-19 in 2021; 2.2% have been hospitalized, and 0.1% have died.
Below are seven things that experts say we need to know about breakthrough cases.
The vaccines remain highly effective in preventing severe COVID.
The Delta variant appears to be increasing the number of fully vaccinated people who still get COVID, experts acknowledge.
That said, the vaccines still significantly decrease the risk of infection and they remain especially effective at preventing hospitalization and/or death.
In a study published Sept. 10 by the federal Centers for Disease Control, people who were not fully vaccinated this spring and summer were four and a half times more likely to be infected by the virus; 10 times more likely to be hospitalized with severe COVID and 11 times more likely to die.
Among U.S. adults without immunocompromised conditions, vaccine effectiveness against COVID-19 hospitalization was 93% for the Moderna vaccine, 88% for Pfizer and 71% for the Johnson & Johnson shot, the CDC reported Friday, Sept. 17. The study looked at 3,600 adults hospitalized between March 11 to Aug. 15.
The more who are vaccinated, the higher the proportion of breakthrough cases.
It’s just a matter of math that the proportion of breakthrough cases will grow as vaccination rates increase, the experts say.
As an example on how that math works: Take an outbreak that infects 2.5% of the population and a vaccine that is 80% effective in preventing infection.
In that scenario, if you had 10,000 people, that’s 250 people who get infected if no one is vaccinated.
If 50% are vaccinated, that’s 125 cases among unvaccinated residents and 25 cases among those who are vaccinated: 150 total cases, with 20% of those cases as breakthroughs -- and 100 cases prevented by vaccination.
If 75% are vaccinated, then 63 of the 2,500 unvaccinated persons are infected, with 37 breakthrough cases among the 7,500 vaccinated persons. That’s 100 total cases, with 33% as breakthroughs. But there also are now 150 cases prevented by vaccination – even though breakthrough cases are a much bigger proportion of the total.
“The more people who are actually vaccinated, the higher proportion of the overall cases are going to be breakthroughs, even though the vaccines are still working,” said Josh Petrie, a University of Michigan epidemiologist.
“So the breakthrough cases will increase and appear to be contributing to a higher proportion of cases,” he said. “But what you don’t see are those prevented cases and those are also growing by quite a bit.”
Senior citizens have high vaccination rates, but also are a disproportionate number of breakthrough hospitalizations and deaths
The math is further complicated by the fact that the people most susceptible to breakthrough cases are senior citizens and people who are immunocompromised -- groups that also have high vaccination rates.
“That’s an important context, too,” Petrie said.
In Michigan, 83% of people age 65 and older are fully vaccinated, compared to 44% for the rest of the population, including those too young to be vaccinated.
Even through seniors are much more likely to be vaccinated, they also are more prone to breakthrough cases because they have weaker immune systems and vaccines are less likely to generate a robust response of antibodies.
And a senior who experiences a breakthrough case is more likely to be hospitalized, simply because the biggest risk factor for COVID hospitalization is age.
About 70% of breakthrough cases that resulted in hospitalization and 87% that resulted in deaths have involved individuals age 65 and older, according to the federal Centers for Disease Control.
Likewise, younger adults with significant health issues or are immunocompromised -- the other groups especially vulnerable to COVID complications -- also are highly likely to be vaccinated.
Among fully vaccinated people who ended up hospitalized for severe COVID, “the vast majority either, No. 1, have significant medical co-morbidities; No. 2, they’re immune-compromised, or No. 3, they’re elderly people with immunosenscence,” which is the weakening of the immune system that occurs with age, Sullivan said.
Breakthrough hospitalizations and deaths include people with asymptomatic COVID
Sullivan makes another point: Data on hospitalizations and deaths for COVID breakthrough cases includes patients who are severely ill with something else.
He estimates that “40 to 50%” of breakthrough cases at Spectrum are actually hospitalized for reasons other than COVID, but test positive for the virus during admission.
“We’ve seen that all along,” Sullivan said. “We sometimes get unvaccinated patients who come in for something else and it’s an incidental discovery (that they have COVID). But it’s a very small minority of those patients. The vast majority of unvaccinated patients who get admitted and test positive for COVID are having respiratory complaints and COVID is the reason for the hospitalization.”
To understand why such “incidental discoveries” are more common in vaccinated vs. unvaccinated patients, consider the math and the demographics.
In regards to the demographics: People who test positive for COVID before an elective procedure are likely to have their procedure rescheduled. So the group who test positive but hospitalized for other reasons are largely there for a medical emergency -- typically senior citizens or people with serious health problems, individuals who are also likely to be vaccinated.
Now look at the math: Say a hospital has 50 patients who have tested positive for COVID, of which 10 are fully vaccinated, and five of the 50 COVID cases are incidental discoveries.
If four of the five incidental discovery cases are vaccinated, that’s 40% of the hospital’s 10 breakthrough cases. And that means only one of the 40 unvaccinated patients is an incidental discovery case, or 2.5% -- a much smaller slice of a much bigger pie.
Nationally, about 25% of fully vaccinated people with COVID are people hospitalized for other reasons, according to the CDC, and about 21% of the death reports on breakthrough cases involve people who were asymptomatic or the death was not COVID-related.
“We’ve vaccinated some people that are 100 years old,” said Linda Vail, head of the Ingham County Health Department. “If you look at some of those, quote, breakthrough deaths, they’re really ill with other things. But if you’re infected with COVID and die within 30 days of natural causes, it’s listed as a contributing cause and counted as a COVID death.”
The risk of COVID-19 hospitalization is very low for a younger adult who is healthy and fully vaccinated
Statistically, a fully vaccinated person under 65 and healthy is much more likely to get injured in a car accident than get hospitalized with COVID-19.
“I have not heard of a young, healthy person who’s like 35, doesn’t have any medical co-morbidities and is fully vaccinated but ended up in the hospital with severe COVID,” Sullivan said. “I’m sure it’s out there, but those are extremely rare.”
On the flip side, Sullivan said, he’s had a number of unvaccinated patients this summer who fit the profile of a young, healthy 30-something who ends up severely ill.
“I’ve had lots of those in the hospital,” Sullivan said. “Some pretty bad cases.”
Likewise, Rosenblat said, “the hospitalizations and deaths that we’ve had from this most recent run of COVID, almost exclusively it’s been among the unvaccinated.”
No vaccine is 100% effective
“I think people need to really understand these vaccines were never, ever designed to completely prevent infection,” Sullivan said. “They were designed to limit the severity of infection, and keep people out of the hospital.”
While the vaccines performed extraordinary well against the original strain of the virus, they’ve become less effective is preventing symptomatic illness caused by the Delta strain, experts say.
The big reason: The Delta strain creates a much bigger viral load in the upper respiratory system, and the antibodies generated by the vaccines don’t kick in until the infection is more systemic. But that’s still much faster than if someone is unvaccinated and lacks natural immunity.
“If you weren’t vaccinated, it takes your body a good five to eight days to really ramp up the immune response to start noticing this virus and try to kick it out,” Sullivan said. “If you’re vaccinated, that process starts within 24 hours. That’s why the vast majority of vaccinated patients, if they do get infected, have a very mild illness or are asymptomatic. But it’s not shocking that we see breakthrough infections.”
That’s particularly true considering the high community transmission rates in the United States right now, said Linda Vail, head of the Ingham County Health Department.
She used the analogy of her attempts to ward off mosquitos during a recent trip to northern Minnesota. While her mosquito repellant reduced the number of mosquito bites, the swarms were so thick at times the repellant could only reduce the number of bites, not totally eliminate them.
And just as there are “tons and tons and tons” of mosquitos in northern Minnesota, Vail said, there’s “tons and tons and tons of virus out there” right now and it becomes difficult to avoid.
But vaccination, like mosquito repellant, does lower the risk of exposure even in the most trying of circumstances, she said.
Fully vaccinated? Still wear a mask
Even though the threat of death or hospitalization is relatively low for the fully vaccinated, the rise in breakthrough cases is significant enough that health experts advise fully vaccinated people to use a mask in indoor public spaces and crowded outdoor gatherings.
That’s to reduce the threat of a breakthrough case, which – even if it’s not severe – can still make for a miserable few days. “There’s the occasional breakthrough case where people get pretty sick for a week,” Vail said. “It’s not common, but it happens. I just had one of our community leaders reach out to me. Her husband got exposed at work, now they both have COVID and it’s fever, muscle aches, all the sort of stuff.”
Just as significant, Petrie says, is that anyone with COVID – vaccinated or not – can spread it to others before they are even aware they are sick, which is why wearing a mask is important even for someone not worried about getting sick themselves.
“I think we still do have that social responsibility to be careful and try not to infect others, given that we do have a large number of people who are unvaccinated, which includes most children,” Petrie said.
“Vaccines are our best tool at reducing these outbreaks, but masks are certainly the second-best tool,” he added. “Given that we know these breakthrough infections can happen in fully vaccinated people and that they can transmit the virus, certainly in situations like we are now with high transmission rates, everyone should be masking indoors right now.”
Read more on MLive:
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