Only 1.4% of cases involved people who received two doses of vaccine.
Nearly all patients affected by an ongoing chickenpox outbreak in New York are not vaccinated, according to a report released Thursday.
The outbreak was first identified by city health officials in October 2022 and was found to affect people who had recently migrated from or through Central and South America and were living in a shelter or residential facility.
The report, co-authored by several New York City agencies and the Centers for Disease Control and Prevention, examined patient interviews and medical record reviews conducted by the Department of Health and Mental Hygiene (DOHMH) of the city.
Between September 2022 and March 2024, 873 people who tested positive for chickenpox were linked to the outbreak, according to the report.
Of the patients, 91.9% had no documentation that they had received a varicella vaccine before the onset of symptoms. The data showed that 6.8% had received at least one dose and only 1.4% had received two doses.
There are two chickenpox vaccines licensed in the United States. The first contains only the chickenpox vaccine and can be administered to children in two doses: the first between 12 and 15 months and the second between 4 and 6 years.
The second contains a combination of the chickenpox vaccine and the measles, mumps and rubella vaccine and is authorized for children between 12 months and 12 years.
Studies have shown that the vaccine that protects only against chickenpox is 82% effective against any form after one dose and 92% effective after two doses, according to the CDC. Receiving one or two doses is 100% effective against severe chickenpox.
The U.S. chickenpox vaccination program began in 1995 and has been a major success, reducing overall annual cases by 97%, the CDC said.
The report also provides breakdowns by age and sources of transmission. The majority of cases – 53% – involved people aged 4 to 18. Adults over 18 years old represented 29.4% of cases and children under 4 years old represented 17.5% of cases.
Among the 780 patients who knew where they contracted the disease, 41.3% were exposed in shelters or residential settings while 39.4% of cases were imported, meaning the incubation period had place before arriving in New York. School transmission represented only 1.2% of cases.
According to the report, many recent migrants come from countries that do not have routine chickenpox vaccination programs or that have a high incidence of chickenpox. Among countries that include varicella vaccination as part of routine immunizations, programs may have been disrupted due to COVID-19 or political instability.
“This outbreak highlights the importance of limiting transmission by achieving and maintaining high (varicella) vaccination coverage and the need for rapid, large-scale vaccination efforts in light of ongoing imports and exposures in U.S. shelters and residential facilities,” the report’s authors wrote.
Some people may suffer complications from chickenpox and require hospitalization, but hospitalizations and deaths from chickenpox are rare these days due to the U.S. vaccination program, according to the CDC.
News Source : abcnews.go.com
Gn Health
