Philadelphia city health officials report a small but notable increase in reported, unvaccinated varicella (chickenpox) cases among children compared with activity since 2020.
The recent increase includes outbreaks at 2 schools in the city, according to the Philadelphia Department of Public Health (PDPH).
This prompted PDPH to issue a health advisory to physicians.
According to health officials:
Acute varicella, or chickenpox, is a contagious, acute viral illness that causes a generalized pruritic, erythematous vesicular rash. Illness often begins with a mild prodrome of fever and malaise. In children, rash may be the first sign of illness. In unvaccinated individuals, varicella rash progresses rapidly from macular to papular to vesicular lesions before crusting. There are usually 250-500 lesions on the body in various stages. Vaccinated people usually have no prodrome and milder disease with fewer than 50 lesions. People are contagious from 2 days before the rash starts, until all lesions are crusted. Vaccinated people with mild breakthrough disease are less contagious than those who are unvaccinated. Varicella is spread through inhalation of aerosols from vesicular fluid of skin lesions and direct contact with skin lesions of someone with acute varicella or zoster. Spread from oropharyngeal secretions from a person with varicella may also occur but to a lesser extent. The incubation period ranges from 10 to 21 days, with an average of 14 to 16 days. Individuals who become infected from a contact at home often have more severe disease than the index case.
Prior to the introduction of varicella vaccine, 4 million people were infected with varicella each year,10,500- 13,500 were hospitalized, and 100-150 people died annually.