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COVID-19 vaccinated infections: what you need to know

With coronavirus cases spreading rapidly throughout California and the country, reports of infections among those fully vaccinated against COVID-19 are gaining more and more attention.

But while these “groundbreaking” cases are sometimes presented as a precautionary narrative – a signal of vaccine shortcomings – the reality is that vaccinations remain as effective as ever where it counts: protecting people from serious disease.

That remains true, officials say, even as Los Angeles County health officials shared a seemingly worrying data point on Thursday: 20% of newly diagnosed coronavirus cases in June were among people vaccinated. Less than two weeks ago, they said more than 99% of COVID-19 cases were among the unvaccinated.

At first glance, these numbers may seem at odds with each other. But a closer look at the data highlights some key findings cited by public health experts, epidemiologists and infectious disease experts in California and by federal officials.

Two things are happening: More than half of Californians are now fully vaccinated, but transmission of the coronavirus has increased. And while rates of coronavirus cases increase in both vaccinated and unvaccinated people, rates continue to be much worse in unvaccinated people – a trend that is expected when viral transmission increases.

Why are cases among vaccinated people increasing?

Both of the following statements can be true at the same time:

Between December 7 and June 7, the unvaccinated accounted for 99.6% of LA County coronavirus cases, 98.7% of COVID-19 hospitalizations, and 99.8% of deaths.

Of all the confirmed coronavirus cases across the county in June, 20% were in fully vaccinated residents.

The first sentence talks about the extraordinary effectiveness of vaccines. Yes, the period between December 7 and June 7 covers a period when vaccine supply was limited. But it also provides a perspective on what hospitals see and explains why doctors are so convinced of the effectiveness and importance of vaccines: extraordinarily few hospitalizations and deaths have occurred among those vaccinated.

This latter percentage is not as surprising as it seems at first glance.

Suppose, for example, that there were about 1,000 cases of coronavirus in one month among fully vaccinated people, and there were 4,000 additional cases of coronavirus among unvaccinated or partially unvaccinated people. In this community, a population of 10 million people was divided: half were vaccinated and half were not.

One could focus on how 20% of coronavirus cases have happened among those vaccinated.

But it could also be pointed out that, per 100,000 inhabitants, 10 vaccinated people tested positive and 40 unvaccinated people tested positive. This means that unvaccinated people, in this hypothetical example, are four times more likely to test positive for the virus.

Statewide, officials note that while there are cases of infection of people who have been vaccinated, the risk remains much more pronounced for those not vaccinated.

From July 7 to 14, the average case rate among unvaccinated Californians was 13 per 100,000, according to the state’s Department of Public Health. Among those who had been vaccinated, the comparable figure was 2 per 100,000.

Vaccinations offer high protection but are not 100%

There is overwhelming evidence that the COVID-19 vaccinations used in the United States continue to offer a high degree of protection – but not 100% – against serious illness, hospitalization and death.

Earlier this week, Dr.Anthony Fauci, the U.S. government’s top infectious disease expert, cited data showing that the Pfizer-BioNTech and Moderna vaccines were 95% and 94% effective, respectively, compared to the Symptomatic COVID-19. And in the United States, the Johnson & Johnson single injection vaccine was 72% effective against a clinically recognizable disease.

“Infections after vaccination are expected. No vaccine is 100% effective, ”he said. “However, even if a vaccine does not completely protect against infection, it usually protects against serious illness if it is successful.”

Nationally, more than 97% of people now hospitalized with COVID-19 have not been vaccinated, according to Dr. Rochelle Walensky, director of the U.S. Centers for Disease Control and Prevention.

“While seat belts don’t prevent everything that can happen in a car accident, they provide great protection – so much so that we all use them regularly,” said Barbara Ferrer, director of health. LA County Public Authority. “It wouldn’t really make sense not to use a seat belt just because it doesn’t prevent all injuries from car crashes.”

Likewise, she continued, “Rejecting a COVID vaccine because it doesn’t offer 100% protection really ignores the powerful benefits.”

People with weakened immune systems should always be especially careful to talk to their doctor about additional protective measures they may want to take.

California failed to achieve “collective immunity”

Despite all of the progress California has made in terms of vaccination, it is now clear that the state still has not achieved “herd immunity” – the level at which enough people have been vaccinated or have obtained natural immunity to. protect the wider population from the virus.

Even the highest vaccination rates in the San Francisco Bay Area are not high enough to protect the region from the increasing number of cases.

Most Bay Area health workers have urged everyone to wear masks in indoor public spaces, regardless of immunization status. And health officials in Contra Costa, Santa Clara and San Francisco counties are urging employers to consider requiring their workers to get vaccinated.

When the transmission of the coronavirus increases, the immune system of fully vaccinated people may come under increased pressure. And officials say people who are more fully vaccinated, if tested, are to be expected to be positive for the coronavirus.

Consider a fully vaccinated person walking into a crowded room with many unvaccinated people, but there are only two infected and contagious people.

“My chances [as a vaccinated person] to be infected were really, really small, ”Ferrer said.

But let’s say the room is filled with 30 unvaccinated infected people. In this case, “my chances – even as a fully vaccinated person – have just increased” of contracting a coronavirus infection, she continued.

However, officials note that unvaccinated people are still much more likely to test positive for the virus than those who have rolled up their sleeves.

In early July, per 100,000 people in LA County, about nine unvaccinated or only partially vaccinated tested positive for the coronavirus daily, according to a table released by the Department of Public Health. This is much higher than the daily case rate for fully vaccinated people, for whom less than two in 100,000 residents have tested positive.

COVID-19 vaccinated infections: what you need to know

Earlier this year, some initial reports from India suggested that the strain of coronavirus that later became known as the Delta variant was of particular concern as so many healthcare workers who had been fully vaccinated were nonetheless infected.

But a later analysis later suggested that the vaccines continue to be effective.

It’s not that the Delta variant was more likely to break the immunity offered by vaccines compared to previous strains of the coronavirus. This is because the increasing circulation of the virus will, as might be expected, lead to more vaccinated people ultimately testing positive.

When health officials say a vaccine is 90% effective, that means 10% of the time it is not effective, said Dr George Rutherford, epidemiologist at UC San Francisco, earlier this year. . The higher the number of people exposed to the coronavirus, the higher the number of so-called “revolutionary” infections.

“It might not have as much to do with the variations as it does with the intensity of the exposure,” Rutherford said.

It’s also important to note that in settings where a high percentage of people are vaccinated, cases remain low, as do hospitalizations and deaths.

In May and June 2020, while the shots were still six months away from public distribution, there were at least 52 outbreaks of the coronavirus in nursing homes in LA County, resulting in more than 2,300 cases, 575 hospitalizations and 333 deaths.

But in June and July, with around 85% of nursing home staff and residents now fully immunized, there were only eight outbreaks, resulting in just 19 cases, one hospitalization and no deaths.

COVID-19 vaccinated infections: what you need to know

A vaccinated person who is infected usually has less to worry about

Not all positive coronavirus cases warrant the same level of concern.

Some vaccinated people who are infected may still feel ugly and experience uncomfortable symptoms. But data consistently shows these people have a much better chance of not needing hospitalization than an unvaccinated person.

“Even for fully vaccinated people who are infected, they are much less likely to get as ill as unvaccinated people, require hospitalization and die,” Ferrer said.

Fauci said the level of coronavirus in the upper throat of an infected and vaccinated person is “considerably less” than in an unvaccinated person.

Fewer viruses mean less severity of the disease.

“This is exactly what your vaccine is supposed to do: it fights the infection in your nose and lowers the viral load, and you have no symptoms,” said Dr Monica Gandhi, an infectious disease expert at UC San Francisco. this month. “I don’t call it vaccine failure. I call it successful because that’s exactly what your vaccine is supposed to do.

Increasingly high transmission rates and the return of masks

One of the reasons LA County is now requiring everyone to wear masks in indoor public places, regardless of immunization status, is to get more unvaccinated people back into the habit of using blankets. -faces in the hope of reducing disease transmission.

Another reason is the fear that those vaccinated could – in a very small number of situations, according to Ferrer – become carriers of the virus with no or very mild symptoms and be able to unknowingly infect other people.

It’s reasonable to assume that an infected vaccinated person will be less likely than an unvaccinated person to pass the virus on to someone else, Fauci said. This is because vaccinated people who are infected have significantly lower levels of the virus in their throats than unvaccinated people.

“So even though we see infections after vaccination (…) the efficacy against serious illness is still substantial,” he said.

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