There is no vaccine for COVID-19 yet, but a handful of companies such as Pfizer and Moderna Inc are in final-stage trials of their experimental vaccines.
It is impossible to evaluate exactly where someone contracted the virus.
The CDC said transmission occurred in poorly ventilated and enclosed spaces that often involved activities that caused heavier breathing, like singing or exercise.
A report published online by the CDC last month found “evidence of asymptomatic transmission of COVID-19 on an airplane.”
What is even more worrying is that two-thirds of parents don’t thing that getting their kids vaccinated against the flu is more pressing this year.
New research shows the fear that the vaccine approval process is being fast-tracked is causing Americans to worry the vaccine won't be safe, and as a result, they are less likely to get vaccinated.
"Long flights not only can lead to importation of COVID-19 cases but also can provide conditions for superspreader events," significant findings show as countries resume international travel.
Redfield, head of the federal government's disease control agency, made his comments in testimony before a US Senate panel.
The New York Times had earlier reported that the CDC had contacted officials in all 50 states and five large cities with the documents.