Wednesday, August 25, 2021

Rising number of breakthrough Delta infections among fully vaccinated

Chicago: A quarter of Los Angeles residents who caught COVID from May to July this year as the Delta variant surged were fully vaccinated.

The data, published in the US Centres for Disease Control and Prevention’s weekly report on death and disease, shows an increase in “breakthrough” infections among those who had both doses of a coronavirus vaccine.

The centre is relying on data from cohorts, such as the Los Angeles County study, to determine whether Americans need a third dose of COVID-19 vaccines to increase protection. Government scientists last week laid out a strategy for booster doses beginning on September 20, pending reviews from the US Food and Drug Administration and the CDC.

While a quarter of the COVID infections in the Los Angeles study were in the fully vaccinated, fewer than one in 20 was hospitalised.
While a quarter of the COVID infections in the Los Angeles study were in the fully vaccinated, fewer than one in 20 was hospitalised. CREDIT:AP

The new data released on Tuesday involved more than 43,000 reported infections among Los Angeles County residents aged 16 and older. Of them, 10,895, or 25.3 per cent occurred in fully vaccinated persons, and 1431, or 3.3 per cent, were in partially vaccinated persons. The majority of infections, however, were among the unvaccinated: 30,801 cases, or 71.4 per cent of the cohort.

The vaccines did, however, protect individuals from more severe symptoms. According to the study, only 3.2 percent of fully vaccinated individuals who tested positive for coronavirus were hospitalised, just 0.05 per cent were admitted to an intensive care unit and 0.25 per cent were placed on a ventilator.

Among the unvaccinated who caught COVID, 7.5 per cent were hospitalised, 1.5 per cent were admitted to an intensive care unit and 0.5 per cent required breathing support with a mechanical ventilator.

In addition to the LA County data, the CDC on Tuesday released an update on a study of healthcare workers that showed a significant drop in vaccine effectiveness among vaccinated frontline workers in eight states who became infected with the coronavirus.

The effectiveness of COVID-19 vaccines among healthcare workers declined to 66 per cent after the Delta variant became dominant, compared with 91 per cent before it arose, according to the report.

The vaccines are still protective, the centre said, and the finding must be interpreted with caution, as vaccine effectiveness might wane over time and the estimates of efficacy were imprecise.

“Although these interim findings suggest a moderate reduction in the effectiveness of Covid-19 vaccines in preventing infection, the sustained two-thirds reduction in infection risk underscores the continued importance and benefits of Covid-19 vaccination,” researchers wrote in the agency’s Morbidity and Mortality Weekly Report.

The findings echo earlier evidence from Israel and the UK suggesting COVID-19 vaccines lost some potency in preventing infections over time as the Delta variant spread.

The observational study tracked more than 4,000 health-care workers, first responders, and other front-line personnel in eight locations across six states from December 2020 to August 2021. They were tested weekly for COVID-19 infection, and about 83 per cent were vaccinated.

About two-thirds of those vaccinated had received the Pfizer shot, 2 per cent received Johnson & Johnson’s, and the rest received the Moderna vaccine.


Q & A on Delta

The rise of Delta, which is far more easily transmitted from person to person than previous strains of the virus, has made going out in public riskier. That’s one reason why the Centers for Disease Control and Prevention (CDC) recently changed its masking recommendations—it now advises vaccinated people in areas with high levels of virus to wear a mask indoors. Figuring out when to take risks and when not to is largely a matter of individual circumstance and preference. For instance, people with weakened immune systems should be more cautious than those with robust immune systems. Here are answers to some other common questions:

Q: How great is the risk of getting sick if you’ve gotten the vaccine?

It depends on the vaccine. A study published in the New England Journal of Medicine in July showed that the twoshot Pfizer mRNA vaccine was 88 percent effective in preventing illness due to the Delta variant, down from 93.7 percent for the Alpha variant. The Moderna mRNA shot is thought to offer similar protection. The study found that the Astra-Zeneca vaccine was 67 percent effective against Delta, as opposed to 74.5 for Alpha.

Q: If vaccinated people can still be infected, should they worry about being able to transmit the virus to others?

Yes, but not as much as unvaccinated people should. According to internal CDC documents recently obtained by The Washington Post, vaccinated people who have been infected with the Delta variant may spread the virus as efficiently as unvaccinated people who are infected. Delta tends to concentrate in the nose and throat, which is why the C.D.C. wants everyone to mask up. However, because vaccinated people tend to have stronger immune responses to the virus, they are probably contagious for only a short time—though this scenario has not been studied rigorously.

Q: Can vaccinated people who show symptoms develop long-haul COVID-19?

Little is known about longhaul COVID. In a recent study of health care workers, 19 percent of vaccinated people who got sick still had symptoms after six weeks. Keep in mind that this is only one study with relatively few participants, so firm conclusions will have to wait for more data.

Q: When will children under the age of 12 be eligible for a shot?

Current estimates range from as little as a month or two to well into 2022. On the far side of the range: FDA officials say they expect children under 12 to be eligible for vaccination by midwinter, after another four to six months of clinical trials. Pfizer, though, is more optimistic. In June, it began a study of 4,500 kids aged 5-to-11 in the U.S., Poland, Finland and Spain and hopes to have enough data collected by September to ask officials for an emergency use authorization.

Q: How do doctors determine which variant you have?

COVID-19 tests don’t identify variants. To find out how prevalent a variant is, the CDC takes samples, identifies them by sequencing their genetic material and then estimates what proportion of infections a given variant accounts for.

Q: Are the symptoms different between the variants?

Symptoms from many variants are similar to those of the original virus—fever, dry cough, shortness of breath. However, Delta can also manifest more like a bad cold, with a runny nose, sore throat and headache. Recently, reports of loss of smell and taste have become less common, according to the Zoe Covid Symptom study.

Q: When does the immunity from the vaccine start to wane? Is it the same for mRNA vaccines and others?

Pfizer recently said that the effectiveness of its mRNA vaccine declines to 84 percent about four to six months after the second shot, based on an internal study that has not yet been peer reviewed. A study in the journal Nature suggested that the mRNA vaccines have potentially long-lasting immunity.

Q: Will everyone eventually need booster shots? Or only those who are elderly and/or immunocompromised?

It depends in part on what kind of variants arise in the future. For now, experts do not foresee a need for most healthy vaccinated people to get booster shots, but that could change. Public health officials have suggested that those with weakened immune systems may need to get boosters this winter.

Q: Is it safe to go back into an office to work?

Safe is a relative term. It depends on an individual’s health, circumstances and tolerance for risk. In an office where everybody is vaccinated and virus levels in the community are low, the risk is small. In an office where many people are unvaccinated and virus levels are high, the risk can be many times higher. The risk for an unvaccinated person is always higher than for a vaccinated person. Vaccinated people who are immunocompromised or are caring for someone who is vulnerable at home may want to keep their potential exposure to the virus as low as possible—which means avoiding crowded, poorly ventilated rooms and wearing masks when indoors with others who may not be vaccinated. Because the Delta variant is so highly transmissible, the CDC now recommends mask wearing for everyone in indoor settings in regions where virus levels are high.

Q: In light of the Delta variant, should we be rethinking resuming regular activities like going to restaurants, sporting events, concerts, flying on planes, etc.?

Most vaccines still offer excellent protection. However, the risk goes up with exposure to the virus—and the Delta variant, with its high transmissibility, has ratcheted up the risk for all activities. Risk tolerance varies from one person to the next, but in general it’s a good idea to be aware of situations that are likely to bring you into contact with high levels of virus. Crowded, stuffy bars are riskier than spacious, well ventilated restaurants. Airplanes usually have good ventilation, but you have to worry about that unmasked, unvaccinated person sitting next to you. If in doubt, wear a mask.

Q: If you’ve already had COVID-19 with mild symptoms, what are the benefits of getting the vaccine?

One big benefit of vaccination is that it reduces the overall level of virus in a population, which makes everyone safer. Some studies also suggest that vaccines provide better protection for longer than natural infection. For instance, a study in China, recently published in The Lancet, showed that only 40 percent of people who had gotten COVID-19 carried antibodies to the coronavirus months later.

Q: If you’ve already had COVID-19 and are getting the vaccine, do you need to get both shots?

Yes. A recent study in the U.K., published in Nature, found that a single shot of the Pfizer vaccine reduced illness from the Delta variant by 33 percent. Two weeks after the second shot, that protection rose to 88 percent.



Biden rejected U.S. intel predictions of rapid Afghan collapse (American Military News)

China sends bombers into Taiwan air defense zone (Washington Times)

Judge blocks Biden’s attempt to limit deportations (Washington Times)

15M votes in 2020 election unaccounted for (Daily Signal)

TX Dems return, quorum established for election integrity bill (Fox News)

FBI knew Ilhan Omar married her brother (Post Millennial)

CDC redefines “fully vaccinated” (Post Millennial)

GOP governors, school districts battle over mask mandates (Associated Press)

GA governor blocks COVID mandate on businesses (Just the News)

Home construction slumps on supply constraints (Epoch Times)

Firearms sales set new record (1945)

FTC refiles Facebook anti-trust lawsuit (CNBC)




1 comment:

Bob Smith said...

"the sustained two-thirds reduction in infection risk underscores the continued importance and benefits of Covid-19 vaccination"

No, it doesn't. The null hypothesis is that natural immunity would have produced this result anyway.