Explained: is ‘natural immunity’ to COVID better than a vaccine?



By: New York Times |

Updated: December 6, 2020 1:11:37 PM





COVID-19 vaccines predictably prevented disease, and they are a much safer bet, experts said. (File)

Following last month’s news of astonishing results from Pfizer and Moderna’s experimental COVID-19 vaccines, Senator Rand Paul tweeted a provocative comparison.

The new vaccines were 90% and 94.5% effective, Paul said. But “naturally acquired” COVID-19 was even better, at 99.9982%, he claimed.

Paul, R-Ky., Is one of many people who, tired of lockdowns and economic losses, have lauded the benefits of contracting the coronavirus. The senator was diagnosed with the disease this year and has argued that surviving an attack of COVID-19 offers more protection and fewer risks than getting vaccinated.

The problem with that logic is that it’s hard to predict who will survive an infection unharmed, said Jennifer Gommerman, an immunologist at the University of Toronto. Given all the unknowns – such as a region’s hospital capacity or the strength of a person’s immune response – choosing the disease over the vaccine is “a very bad decision,” she said.

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The main advantage of a vaccine is that it is predictable and safe, she said. “It has been optimally tailored to generate an effective immune response.”

But what do we know about how immunity to a previous infection compares to the protection offered by the new vaccines? And if you’ve already had COVID – is it safe to get vaccinated? We asked experts to give their opinion on the latest evidence. 📣 Follow Express Explained on Telegram

What makes for a stronger immune response: a natural infection or a vaccine?

The short answer: we don’t know. But COVID-19 vaccines predictably prevented disease, and they are a much safer bet, experts said.

Vaccines for some pathogens, such as pneumococcal bacteria, elicit better immunity than the natural infection. Early evidence suggests that the COVID-19 vaccines may fall into this category. Volunteers who received the Moderna shot had more antibodies – a marker of immune response – in their blood than people who had been ill with COVID-19.

In other cases, however, a natural infection is more potent than a vaccine. For example, having mumps – which can cause infertility in men – generates lifelong immunity, but some people who have received one or two doses of the vaccine still get the disease.

On Paul’s point, the natural immunity to the coronavirus is fortunately quite strong. The vast majority of infected people produce at least some antibodies and immune cells that can fight the infection. And the evidence so far suggests that this protection will last for years, preventing serious illness or even reinfection.

But there is a tremendous dynamic range ”in that immune response, with a 200-fold difference in antibody levels.

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In people who are only mildly ill, the immune protection that can prevent a second infection may diminish within months. “Those people may benefit more from the vaccine than others,” said Bill Hanage, an epidemiologist at Harvard TH Chan School of Public Health.

The diversity in the immune response of natural infection may be due to differences in the amount of virus to which the subject was exposed.

Everyone gets the same dose with a vaccine. “We know the dose that is being administered, and we know that that dose is effective in inducing an immune response,” said Gommerman. “So that’s going to be a variable that is taken off the table when you get the vaccine.”

I am young, healthy and have a low risk of COVID. Why not take my risk with that instead of getting a rushed vaccine?

The experts were unanimous in their answer: COVID-19 is by far the more dangerous option.

“Clearly, one is less problematic for the body to recover from than the other – there is more risk with natural infection,” said Marion Pepper, an immunologist at the University of Washington in Seattle.

People who are obese or with diseases such as diabetes are particularly prone to severe cases of COVID-19. On average, the virus appears to be less risky to younger people, and women tend to do better than men. But beyond those generalized generalizations, doctors don’t know why some people get very sick and die, while others have no symptoms.

For example, people harboring certain mutations in immune genes are more susceptible to the disease, several studies have shown. “So there is a risk factor that has nothing to do with age,” said Gommerman.

In a study of more than 3,000 people ages 18 to 34 who were hospitalized for COVID, 20% required intensive care and 3% died.

“It is true that most people do not go to hospital, most people do not go to intensive care or die,” said Dr. Yvonne Maldonado, who represents the American Academy of Pediatrics at the meetings of the federal Advisory Committee on Immunization Practices.

But “no one is immune from serious illness,” she said. And even if people themselves are not at high risk for COVID, their friends or family can be.

As many as one in three people who recover from COVID have chronic complaints for months afterwards, including exhaustion and a beating heart. This includes people under the age of 35 with no previous health conditions. Some COVID survivors also show troubling signs that their bodies have self-harm, with symptoms similar to those of lupus and rheumatoid arthritis.

COVID vaccines, on the other hand, carry little known risks. They have been tested on tens of thousands of people without serious side effects – at least so far. “Once you start vaccinating millions, you can come across very, very rare events,” Hanage said. “But we should know that they are very, very rare, and much rarer than the side effects associated with natural infection.”

I had COVID. Is It Safe For Me To Get A Vaccine? If so, when can I get one?

It’s safe and probably even beneficial for anyone who’s had COVID to ever get the vaccine, experts said.

“There’s nothing harmful about getting a boost for an immune response you’ve had before,” said Pepper. “You could actually get an even better immune response by boosting the immunity you had from the first infection with a vaccine.”

In fact, Dr. Moncef Slaoui, chief adviser to Operation Warp Speed, at a meeting on Wednesday that up to 10% of the participants in clinical trials for the vaccines were unknowingly infected with the virus. Their immune responses to the vaccine are being analyzed, he said.

If you’ve already had COVID-19, you can afford to wait a while for the vaccine.

Studies by Pepper’s team and others have shown that the immune response evolves in the first few months after infection, but anyone who has had COVID has some level of protection during that time.

“We haven’t seen anyone who doesn’t develop any kind of immune response,” she said. “I don’t think those people will have to rush to get the vaccine in the same way that people who are highly susceptible really do.”

The ACIP, which makes recommendations to the Centers for Disease Control and Prevention on vaccine distribution, said at a meeting Wednesday that people who were not infected should take precedence over those who contracted the virus in the past 90 days.

“At some point we’ll have to figure out if 90 days is the right number,” said Maldonado. But for now, “people who have recent signs of infection probably should not get vaccinated first because so little vaccine is available.”

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