More than 1,000 of the ship’s approximately 4,900 crew members tested positive for Covid-19 after the outbreak. After spending weeks in a port in Guam, the ship returned to sea last month.
The majority – almost 60% – of the study’s sailors who had antibodies had neutralizers, “a promising indicator of at least short-term immunity,” the researchers wrote.
Most reported mild or no symptoms, and those who took preventive measures – such as face masks and social distancing – were less likely to be infected.
With a number of young people reporting mild, atypical or absent symptoms of the virus, “symptom-based surveillance may not detect all infections,” the investigators wrote.
Most tested positive for antibodies
The report, released Tuesday, included a sample of 382 military personnel, with a median age of 30. According to the report, three-quarters were men.
Almost 60% of them tested positive for antibodies, and among them, 59% had also developed neutralizing antibodies by the time their blood samples were taken.
Neutralizing antibodies bind to the virus, potentially preventing it from attacking human cells. In a handful of participants, these antibodies were detected more than 40 days after the onset of their symptoms.
However, as the data come from a single point in time, they note that longer studies will be needed to definitively show whether and for how long these antibodies could protect against the virus.
Lower infection rate among those who took protective measures
Those who took preventive measures were also less likely to be infected.
Sailors who wore face covers were less likely to be infected (55.8% compared to 80.8%), as were those who avoided common areas (53.8% compared to 67.5%) and practiced distance physical (54.7% versus 70.0%).
The symptoms most closely associated with Covid-19 in this sample were loss of taste or odor, muscle pain, fever, and chills.
Two were hospitalized among the 238 in the study confirmed to be infected with the virus.
Officials are working to “adapt our public health practices to the unique characteristics of this adversary whose secret weapon, as you know, is the ability to be transmitted by an individual before he knows he is infected” , Rear Admiral Bruce Gillingham, The US Navy general surgeon told reporters Tuesday.
CNN Theresa Waldrop and Barbara Starr contributed to this report.