Rob Richter had a dry cough and some congestion, and he was a little tired, but mostly he was annoyed. It was the morning of July 12, and a rapid test he took at home showed he was positive for COVID-19.

It was less than two days after the Mystic resident had returned from a conference in Boston, where he believes he was exposed ― and a little under nine months since he contracted COVID-19 the first time.

It was late October when Richter, 62, first got COVID-19, he believes from a friend with whom he drove to a yoga class. He works as director of arts programming at Connecticut College and had the ability to get frequent PCR tests on campus, so he took multiple tests.

This infection meant he had to cancel travel to a Peace Corps reunion, where he was supposed to represent his late father, who served as deputy director of the Peace Corps in Kenya in the 1960s. Richter, who got his first booster shot shortly before his first case and his second booster in April, said both cases were mild.

Reinfections were relatively rare last year, but that changed when the omicron variant surged in the U.S. in winter. The novel coronavirus continues to evolve, and the subvariant dubbed BA.5 accounted for 81.9% of new cases for the week ending July 23, according to the Centers for Disease Control and Prevention.

One study followed more than 250,000 people in Serbia who had laboratory-confirmed COVID-19 between March 2020 and October 2021, following them until Jan. 31, and recorded nearly 87% of the reinfections in January. The reinfection risk was higher among women, health care workers and people with fewer vaccine doses.

According to data from the United Kingdom, the rate of reinfections was fairly steady from May to December of last year before rising dramatically, peaking in April and then dropping slightly. People were more likely to be reinfected if they were asymptomatic in their first infection and are younger.

The U.S. doesn’t track reinfections, but some states do. New York, for example, reported the most reinfections for the week beginning Dec. 27.

Dr. Prakash Kandel, an inpatient doctor who treats COVID-19 patients at Lawrence + Memorial Hospital in New London, said he saw a few reinfections during the delta variant wave last year but it’s more common now. He said while vaccinated people can get reinfected, the vaccine still provides protection against severe infection.

Most of the people he sees are not in the hospital specifically for COVID-19. Elderly people may come to the hospital for nonspecific symptoms and then test positive, he said, and “it’s hard to tell the symptoms whether it’s purely from COVID or it’s something else, because it’s multiple things going on at the same time.”

If it seems like more people are getting reinfected now, it’s partially due to timing: A lot of people in the U.S. contracted COVID-19 in January and February, and the immunity built up from those infections has waned. The CDC estimated that the percentage of people in the U.S. with at least one infection increased from 33.5% at the end of December to 57.7% at the end of February.

“I think there’s two things going on,” said Dr. Ted Cohen, an infectious disease epidemiologist at the Yale School of Public Health. “The first is that we have a lot of people who have been infected at this point, and that’s necessary to be reinfected, obviously, and secondly, some of these new variants that are circulating, especially BA.5, seems to have an important capacity to evade previous immune responses.”

It's difficult to estimate how many people have gotten COVID-19 at least once because so many people test positive on at-home rapid tests, which aren’t reported.

But Cohen is a contributor to Covidestim, covidestim.org, a collaboration between departments at the Yale School of Public Health and Harvard T.H. Chan School of Public Health that uses a statistical model to try “to paint a complete, current, and granular picture of the U.S. COVID-19 epidemic.”

The model estimates that Connecticut has seen 131,000 infections per 100,000 people to date ― meaning that on average, people have been infected more than once, even though some people have yet to be infected at all. But this is their “best guess,” and Cohen said there’s “wide uncertainty” around the number of infections in the state.

How do symptoms compare?

Kandel hasn’t seen anyone who was hospitalized for COVID-19 during a reinfection but not during the first infection, and both he and Cohen said reinfections on average are likely to be less severe than initial infections.

The Serbian study, which ran through January, found that the hospitalization rate for a reinfection was 1.08%, compared to 3.66% for a first infection.

But there’s still risk.

A preprint posted in June, which hasn’t yet been peer-reviewed and is under review at the journal publisher Nature Portfolio, found that compared to people with one infection, reinfection “contributes additional risks” of hospitalization, other adverse health outcomes and even death from any cause.

Researchers at the Washington University School of Medicine and VA Saint Louis Health Care System found that reinfected people exhibited increased risk of cardiovascular disorders, diabetes, fatigue, gastrointestinal disorders and more.

The authors said the risks were evident regardless of vaccination status.

The study used U.S. Department of Veterans Affairs databases to look at health outcomes of 38,926 people with two or more COVID-19 infections, which included 246 people with four or more infections. It also included 257,427 people with one infection and a control group of 5.4 million people who had never been infected, but across the groups, only 10% of the participants are women, reflecting the VA population.

The data also showed increased risk of mental health and neurologic disorders from reinfection.

COVID saps your ’oomph’

Mystic resident Maria Saganis, 57, thinks the mental health symptoms of COVID-19 aren’t discussed enough. She said she contracted the coronavirus last September and in early July, respectively, while traveling to Missouri and Los Angeles.

“I was annoyed when I got it, because I’d gone through the vaccines, and then I got hit with it, and when I got hit with it, I couldn’t breathe,” she said of the first infection. “The fatigue alone was debilitating; I didn’t eat for six days. I slept for six days, and honestly, in the middle of it, I was hoping I would just cross over.”

She “just felt extremely dead inside,” something that was particularly rough for someone who works as an intuitive healer.

While she didn’t have a fever or flu-like symptoms the second time, she was fatigued — and still is — “and went through that same depression.” She described it as being in a funk and not feeling like herself, not feeling like she has her usual “oomph.”

Saganis said she had breast cancer in the ’90s but has been free and clear since, and she’s not someone who ever gets colds or the flu.

“It pisses me off. I don’t like being down. I don’t like being in isolation. I don’t like having to quarantine for seven days. It just sucks,” Saganis said. She said she’s heard from clients that they’re also weepy and depressed, that it’s “almost like PMS on steroids.”

How often can someone get reinfected?

Reinfection has been defined as an infection more than 90 days after a previous one. But as new omicron subvariants have emerged and skirted immune protections, University of California San Francisco infectious disease specialist Peter Chin-Hong told The Wall Street Journal that rule of thumb is now “completely out the window.”

An Australian governmental health committee earlier this month advised that the reinfection period be reduced from 12 weeks to 28 days. But it’s still unlikely someone would get reinfected with the same subvariant within a few months.

Chris Kennedy — a Groton native splitting his time between here and Arizona, working as fundraising director for the Vatican Observatory — contracted COVID-19 in January and mid-June.

The first time was just two weeks after receiving the Moderna booster, which followed his unusual vaccine history of being in the AstraZeneca trial and then getting the Johnson & Johnson shot.

Kennedy, 32, thinks he got the coronavirus the first time from traveling to England, though no members of the family with whom he stayed tested positive, and the second time from a wedding.

He described his symptoms the first time as mild, with a sore throat, headache and a little bit of congestion. He said the symptoms the second time were also all above the neck, but the sore throat lasted longer and he had more nasal congestion.

But he said after the first bout, he would wake up after eight hours of sleep feeling like he only got four, and the fatigue lasted for about three months.

e.moser@theday.com