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Ebola Cluster Traced to Vaccinated Taxi Driver Who Appeared to Recover

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NEW YORK (Reuters Health) – This is the story of a taxi driver, a vaccine that may not live up to its billing, and a treatment that seemed to save him from death, only to set the stage for his infection to spread to 91 others in six communities over four months.

The disease is Ebola virus disease (EVD), which kills nearly two-thirds of the people it infects. The story is set amid an outbreak that began in 2018 and lasted into 2020 in the North Kivu province of the Democratic Republic of Congo.

The taxi driver, actually a motorcycle taxi driver, received an Ebola vaccine on December 6, 2018, after coming in contact with a person who had a confirmed case of Ebola.

The vaccine, made by Merck, had been estimated to be 100% effective in one trial and 97.5% effective in another.

But on June 13, 2019, the 25-year-old man developed severe symptoms – fever, nausea, vomiting, myalgia, chest pain and asthenia. Two days later he was at the Ebola treatment unit (ETU) in Mangina. Tests showed he had the Ebola virus in his blood.

The next day, on June 16, he was treated with an experimental monoclonal antibody therapy against the virus, in addition to an intravenous antibiotic (ceftriaxone), the antimalarial agent artesunate-amodiaquine, omeprazole and magnesium.

Thirteen days later, he had recovered enough to be discharged. By then two consecutive polymerase-chain-reaction Ebola tests were negative. Nearly two months later, on August 27, a semen sample from the driver, collected as part of the Congo’s program to follow Ebola survivors, also came back negative.

But on November 25, 149 days after being discharged, the driver developed headache, asthenia, polyarthralgia, myalgia and anorexia. He went to a local health center. The next day, nausea, diarrhea, jaundice, melena, epistaxis and pain in the abdomen, chest and spine developed. It wasn’t clear what he received as treatment in the hospital but his symptoms got worse.

On December 3, after eight days of feeling ill, he was transferred to the Mangina Ebola unit. He tested positive for the virus once again. He developed acute respiratory distress, suffered multiorgan failure or dysfunction, and went into a coma the next day. He died the following day.

“Given that we found no signs of immune deficiencies, this probably was an incidence of temporal or complete vaccine failure,” Dr. Michael Wiley of the College of Public Health at the University of Nebraska Medical Center, in Omaha, and colleagues report in The New England Journal of Medicine. “This finding is in line with those of other studies showing that up to 10% of patients with EVD had been fully vaccinated for at least 10 days before admission to the ETU.”

Serologic data also show that in up to one in five persons, positive Ebola IgG binding titers have not developed one month after vaccination, the authors add. “Combined, these findings arouse concerns about the true effectiveness of rVSVZEBOV,” they write.

When investigators did contact tracing, they identified 29 people who had been exposed to him who subsequently developed Ebola, either in the community or in the local health clinics where he had sought treatment.

Those 29, in turn, had infected 62 other people. Genomic analysis of serum samples confirmed the links to the driver’s infection.

“Taken together, our phylogenetic and epidemiologic data show that the patient’s second EVD (Ebola virus disease) episode was the result of EVD relapse from his initial EBOV (Ebola virus) infection and was not due to reinfection,” Dr. Wiley and colleagues write.

The researchers say it appears that the taxi driver had a persistent Ebola virus infection and experienced a relapse. He showed no signs of immune system deficiency.

“He was symptomatic in the community for a while,” Dr. Wiley told Reuters Health by phone. “You’re not infectious until you’re symptomatic. He probably didn’t think he was infectious because he’d had it before.”

There have been two other cases of a similar relapse, he said, but “this is the first time you have a relapse with further transmission. It gives another example of how a persistent infection can be transmitted.”

It may not be good news for Ebola survivors because “they’re already stigmatized as it is,” Dr. Wiley said. “But the reason it’s being published in The New England Journal of Medicine is that it’s a very rare occurrence” and people should realize that.

Many questions about the case persist, he cautioned. It’s not known whether the virus lies dormant and something triggers a relapse, or if remnants of the virus replicate at a much slower rate, dramatically delaying the symptoms.

“This case report shows the need for continued monitoring of vaccine and therapeutic interventions and the power of having locally available genomic capabilities to support the outbreak response,” the researchers said.

“What we need,” said Dr. Wiley, “is better surveillance mechanisms for when this occurs.”

SOURCE: https://bit.ly/3lUMVYx The New England Journal of Medicine, online March 31, 2021.

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