COVID-19 poses a particular challenge because people with asymptomatic and pre-symptomatic infections can spread the disease – and insufficient contact tracing and testing mean those without symptoms
[Links nur für registrierte Nutzer]. Some scientists estimate that the number of asymptomatic COVID-19 infections in the overall population
[Links nur für registrierte Nutzer] than the number of confirmed cases. Research suggests that undocumented cases of COVID-19 in people who either were asymptomatic or experienced very mild disease could be responsible for
[Links nur für registrierte Nutzer], though other studies
[Links nur für registrierte Nutzer].
In [Links nur für registrierte Nutzer], the CDC tested volunteer health care personnel and other front-line workers at eight U.S. locations for SARS-CoV-2 infections weekly for three months, regardless of symptoms or vaccination status. The researchers found that fully immunized participants were 25 times less likely to test positive for COVID-19 than were those who were unvaccinated. Findings like this imply that if vaccinated people are so well protected from getting infected at all, they are
[Links nur für registrierte Nutzer] the virus. But without contact tracing to track transmission in a larger population, it’s impossible to know if the assumption is true.
What we know for sure is that if someone does get sick with COVID-19 after vaccination, in what is called a “breakthrough infection,”
[Links nur für registrierte Nutzer]. Studies have found that people who tested positive for COVID-19 after getting
[Links nur für registrierte Nutzer] had
[Links nur für registrierte Nutzer] than unvaccinated people who tested positive. The researchers believe the decreased viral load hints that vaccinated people who do contract the virus
[Links nur für registrierte Nutzer] because they will have much less virus that could be spread to others.