New CDC study finds prior COVID infection offered stronger immunity than vaccines during Delta surge



A new study conducted by the U.S. Centers for Disease Control and Prevention found that prior infection with COVID-19 offered stronger protection than vaccination against reinfection and hospitalization during the Delta variant surge last summer and fall.

What are the details?

The study, which analyzed data from May through November of 2021 in California and New York, was published Wednesday in the CDC's Morbidity and Mortality Weekly Report.

It found that in California, only 0.5% of unvaccinated individuals with prior infection were diagnosed with a new infection, and only 0.003% (or 378 people out of 1,370,782) were admitted to the hospital.

The figures were lower than those of vaccinated individuals without prior infection, of whom 1.5% were diagnosed with an infection and 0.007% (or 10,737 people out of 15,484,235) were hospitalized.

Similar data was produced in New York during the same time period, although New York did not produce hospitalization data.

The study also showed that a third group of individuals who were both vaccinated against the virus and had a prior infection — sometimes called "hybrid immunity" — fared the best during the Delta surge. And lastly, a fourth group consisting of unvaccinated individuals without prior infection accounted for by far the most infections and hospitalizations.

In short, the data demonstrated that both vaccination and prior infection produced immune protection against the Delta variant.

What else?

Researchers were keen to note that vaccination remains the safest way to protect oneself against health complications resulting from the virus, since infection-derived immunity carries with it some obvious risks.

“A COVID vaccination helps protect by creating an antibody response without the person having to experience severe illness and death,” Benjamin Silk, one of the study's authors and an epidemiologist at the CDC, said during a call with reporters Wednesday, according to Politico. “Vaccination provides safer protection.”

"Vaccines continue to reduce a person's risk of contracting the virus that causes COVID-19 and are highly effective at preventing severe illness," he added.

Researchers also noted that some of the data was collected at a time when vaccine immunity was fading and before booster shots became widely available.

"Importantly, infection-derived protection was greater after the highly transmissible Delta variant became predominant, coinciding with early declining of vaccine-induced immunity in many persons," the study's authors said, noting that further research was needed to determine the efficacy of vaccine boosters.

Anything else?

Still, for the many who have voiced support for naturally derived immunity and argued that individuals with prior infection should not be subject to vaccine mandates, the new research likely serves as vindication.

Some scientists, such as Dr. Jeffrey Klausner, a professor of medicine and public health at the University of Southern California, believe the study's findings should impact public health policies moving forward.

"No one who cares about public health is ever going to say that it's better to get infected than get vaccinated when we have a safe vaccine," Klausner told NBC News. "But in terms of policy, this supports all the clinical research and other data that suggest that immunity after infection is real, is durable."

Because of that, he said, "policy in the United States should be updated, like in many European countries, to allow for people to go to work, to go to school, if they have evidence of recovery of infection without requiring vaccination."

Stunning new data shows risk of death from Omicron is 91% lower than Delta, CDC-funded study says



The Omicron variant of COVID-19 is far milder than Delta, according to a new study funded by the Centers for Disease Control and Prevention. The eye-opening data revealed that those infected with the Omicron variant are 91% less likely to die than those who are infected than the Delta strain.

The clinical study was conducted by Kaiser Permanente Southern California health care system – which operates 138 medical offices and 13 medical centers, plus has an affiliation with 37 community hospitals in Southern California. The study analyzed 52,297 Omicron cases and 16,982 Delta cases in Southern California between Nov. 30, 2021, and Jan. 1, 2022.

The study found that those infected with the Omicron variant were 53% less likely to have symptomatic hospitalization, had 74% less chance of being administered to the intensive care unit, and had a 91% lower risk of death compared to individuals with the Delta variant. Only one person of the more than 52,000 people with Omicron died, versus 14 deaths in the 16,982 with Delta. In addition, there were zero patients with Omicron who required mechanical ventilation, according to the research.

"Hospital admissions occurred among 235 (0.5%) and 222 (1.3%) of cases with Omicron and Delta variant infections, respectively," the authors of the study said.

Patients infected with Omicron had a median duration of hospital stay of three fewer days than those with Delta.

"During a period with mixed Delta and Omicron variant circulation, SARS-CoV-2 infections with presumed Omicron variant infection were associated with substantially reduced risk of severe clinical endpoints and shorter durations of hospital stay," the authors of the study concluded.

The CDC-funded study – which has not yet been peer-reviewed – did not reveal the ages of those who died or their vaccination status.

On Wednesday, CDC Director Rochelle Walensky shared the study on Twitter.

Despite the promising news, Walensky tempered the optimism by saying, "While less severe, #Omicron is much more transmissible & we are seeing the unprecedented impact. Over 1M cases in a day, 99% of counties with high transmission & strained healthcare systems. Protect against #COVID19: get vaccinated + boosted, wear a mask & stay home if sick."

While speaking at a White House Covid-19 Response Team briefing on Wednesday, Walensky said public health officials will monitor "deaths over the next several weeks to see the impact of Omicron on mortality."

"Given the sheer number of cases, we may see deaths from Omicron, but I suspect the deaths we're seeing now are still from Delta," the CDC head revealed.

While less severe, #Omicron is much more transmissible & we are seeing the unprecedented impact.\n\nOver 1M cases in a day, 99% of counties with high transmission & strained healthcare systems.\n\nProtect against #COVID19: get vaccinated + boosted, wear a mask & stay home if sick.
— Rochelle Walensky, MD, MPH (@Rochelle Walensky, MD, MPH) 1642008210

The Omicron strain became the dominant variant in mid-December and now accounts for an estimated 98.3% of all new cases, according to CDC data.

There were 829,209 cases of COVID-19 in the U.S. on Jan. 12 compared to 90,024 cases on Dec. 12.

On Tuesday, Dr. Anthony Fauci acknowledged how transmissible the Omicron variant is and said nearly everyone will contract it.

"Omicron, with its extraordinary, unprecedented degree of efficiency of transmissibility, will ultimately find just about everybody," Fauci told J. Stephen Morrison – senior vice president of the Center for Strategic and International Studies. "Those who have been vaccinated ... and boosted would get exposed. Some, maybe a lot of them, will get infected but will very likely, with some exceptions, do reasonably well in the sense of not having hospitalization and death."

Also on Tuesday, U.S. Food and Drug Administration acting commissioner Dr. Janet Woodcock said that "most people are going to get COVID."

"I think it's hard to process what's actually happening right now, which is: Most people are going to get COVID," Woodcock said at a Senate Health, Education, Labor and Pensions Committee hearing. "And what we need to do is make sure the hospitals can still function, transportation, you know, other essential services are not disrupted while this happens."

CDC study finds over 80% of US adults have some immunity to COVID, notes prior infection offers similar protection as vaccine



A recent survey of blood donations has found that more than 80% of Americans over the age of 16 have some level of immunity to COVID-19 — a figure that could have massive implications on the country's public health policy moving forward.

The survey, conducted by researchers at the U.S. Centers for Disease Control and Prevention, also found that twice as many people have been infected by the pathogen than have been officially counted, CNN reported. As of Thursday, more than 39 million Americans have tested positive for the virus.

According to CNN, the CDC team, led by Dr. Jefferson Jones embarked on the study to "determine how close the US might be to some kind of herd immunity." Though the news outlet was sure to mention the researchers "do not claim to have any kind of handle on that yet."

They accomplished the task by testing about 1.4 million blood samples provided by 17 different blood collection organizations from all 50 states.

Upon studying the samples, the team found that between July 2020 and May 2021, the percentage of blood samples that carried SARS-CoV-2 spike antibodies increased from 3.5% to 83.3% over that time period.

Based on a sample of blood donations in the United States from July 2020 through May 2021, estimated #SARSCoV2 sero… https://t.co/OyWffTBmRL
— JAMA (@JAMA_current) 1630598403.0

The researchers highlighted the prominent role widespread vaccine efforts have played in raising the percentage. Though they also noted that prior infection provides similar protection against the virus.

"Several large studies have shown that among individuals who are seropositive from prior SARS-CoV-2 infection, COVID-19 incidence is reduced by 80% to 95%, similar to vaccine efficacy estimates," they wrote.

The researchers acknowledged their study has "several limitations," however, including that all of the testing occurred prior to the Delta variant's full emergence in the U.S.

Of note, a recent study out of Israel found that unvaccinated individuals with prior infection were 13 times less likely to contract the Delta variant than vaccinated individuals without prior infection.

Likewise, the study focused only on the presence of antibodies in the blood samples and didn't measure other immune responses, including those involving memory T-cells.

"Additional research is needed on the association between combined seroprevalence, protection, and herd immunity," the researchers wrote.

"The study will continue until at least December 2021, and results will be made available on the CDC's website," they added.

CDC director: Data suggests vaccinated people don't carry COVID-19



Centers for Disease Control and Prevention Director Dr. Rochelle Walensky announced on Monday that scientific evidence suggests people vaccinated against COVID-19 almost never carry the virus.

Appearing for an interview with MSNBC host Rachel Maddow, Walensky said: "Our data from the CDC today suggests that vaccinated people do not carry the virus, don't get sick, and that it's not just in the clinical trials, but it's also in real-world data."

CDC Director Dr. Rochelle Walensky: “Our data from the CDC today suggest that vaccinated people do not carry the vi… https://t.co/SPrrZJJHkb
— The Recount (@The Recount)1617125532.0

On Monday the CDC released a study that found the Pfizer and Moderna vaccines were 90% effective after two doses and were 95% effective in preventing COVID-19. The study looked at nearly 4,000 front-line workers, some of whom were vaccinated and some not, who were tested weekly for COVID-19 between December and March.

Among those who had been vaccinated, only three individuals developed COVID-19 infections, while there were 161 positive COVID-19 cases among those who did not receive a vaccine.

"This is very reassuring news," study lead author Mark Thompson said. "We have a vaccine that's working very well."

On Wednesday, Sen. Rand Paul (R-Ky.) cited Walensky in a tweet that called on White House top health adviser Dr. Anthony Fauci to admit that vaccinated people are not at risk of spreading COVID-19.

"Please end the mask theater now that cdc admits evidence that vaccinated do not carry the virus," Paul said.

paging Dr Fauci:  please end the mask theater now that cdc admits evidence that the vaccinated do not carry the vir… https://t.co/9lXUQfvnOP
— Senator Rand Paul (@Senator Rand Paul)1617204381.0

Earlier this month, Paul and Fauci had a public disagreement over mask-wearing during a Senate hearing on the federal government's COVID-19 response.

Paul argued that there is no data to suggest a vaccinated individual is at risk of carrying or spreading COVID-19 and said that therefore, vaccinated Americans should not have to wear masks or observe social distancing guidelines.

Fauci "totally" disagreed with Paul, warning that new variants of COVID-19 put people at risk of reinfection, but he did not point to a scientific study that shows there is significant risk of that happening.

Paul accused Fauci of "making policy based on conjecture."

Last week, researchers launched a National Institute of Health-backed study to determine if there is significant risk of asymptomatic spread of COVID-19 among people who have received Moderna's vaccine. The study will examine 12,000 college students from 21 different college campuses who volunteer to participate. Half of the volunteers will receive Moderna's vaccine at the onset of the study, while the other half will receive their shots in four months. Researchers will regularly test the students for COVID-19 to see if the vaccine protects against asymptomatic spread.

"We hope that within the next five or so months we'll be able to answer the very important question about whether vaccinated people get infected asymptomatically, and if they do, do they transmit the infection to others," Fauci said during a White House COVID-19 task force briefing on Friday.

In the meantime, the federal government is likely to recommend that people vaccinated for the virus continue to wear masks.