Can people vaccinated against Covid-19 still spread the coronavirus?

When the US Centers for Disease Control and Prevention changed its guidelines about maskwearing on May 13 2021 plenty of Americans were left a little confusedNow anyone who is fully vaccinated can participate in indoor and outdoor activities large or small without wearing a mask or physical distancingAnthony Fauci chief medical adviser to President Joe Biden said the new guideline is based on the evolution of the science and serves as an incentive for the almost twothirds of Americans who are not yet fully vaccinated to go ahead and get the shotBut some people cannot be vaccinated because of underlying conditions Others with weakened immune systems from cancer or medical treatments may not be fully protected by their vaccinations Children aged 12 to 15 became eligible for the PfizerBioNTech vaccine only on May 10 2021And no Covid19 vaccines are yet authorised for the nearly 50 million children in the US younger than 12As restrictions are lifted and people start to leave their masks at home some people worry Can you catch Covid19 from someone whos vaccinatedVaccines dont always prevent infectionResearchers had hoped to design safe Covid19 vaccines that would prevent at least half of the people vaccinated from getting Covid19 symptomsFortunately the vaccines have vastly outperformed expectations For example in 65 million residents of Israel aged 16 years and older the PfizerBioNTech mRNA Covid19 vaccine was found to be 953 per cent effective after both shotsAlso ReadAn online Covid19 memorial is helping keep the memory of the deceased aliveWithin two months among the 47 million fully vaccinated the detectable infections fell by 30fold Similarly in California and Texas only 005 per cent of fully vaccinated health care workers tested positive for Covid19Vaccine developers often hope that in addition to preventing illness their vaccines will achieve sterilising immunity where the vaccination blocks the germ from even being able to get into the body at allThis sterilising immunity means someone whos vaccinated will neither catch the virus nor transmit it further For a vaccine to be effective though it doesnt need to prevent the germ from infecting an immunised personThe Salk inactivated polio vaccine for instance does not completely stop polio virus from growing in the human gutBut it is extremely effective at preventing the crippling disease because it triggers antibodies that block the virus from infecting the brain and spinal cordGood vaccines provide effective and durable training for the bodys immune system so when it actually encounters the diseasecausing pathogen its ready to mount an optimum responseWhen it comes to Covid19 immunologists are still figuring out what they call the correlates of protection factors that predict just how protected someone is against the coronavirusResearchers believe that an optimum amount of neutralising antibodies the type that not only bind the virus but also prevent it from infecting are sufficient to fend off repeat infectionsScientists are also still assessing the durability of immunity that the Covid19 vaccines are providing and where in the body its workingCan a vaccinated person spread coronavirusImmunologists expect vaccines that protect against viral illnesses to also reduce transmission of the virus after vaccination But its actually tricky to figure out for sure if vaccinated people are not spreading the germCovid19 poses a particular challenge because people with asymptomatic and presymptomatic infections can spread the disease and insufficient contact tracing and testing mean those without symptoms are rarely detectedSome scientists estimate that the number of asymptomatic Covid19 infections in the overall population could be 3 to 20 times higher than the number of confirmed casesResearch suggests that undocumented cases of Covid19 in people who either were asymptomatic or experienced very mild disease could be responsible for up to 86 per cent of all infections though other studies contradict the high estimatesIn one study the CDC tested volunteer health care personnel and other frontline workers at eight US locations for SARSCoV2 infections weekly for three months regardless of symptoms or vaccination statusThe researchers found that fully immunised participants were 25 times less likely to test positive for Covid19 than were those who were unvaccinatedFindings like this imply that if vaccinated people are so well protected from getting infected at all they are also unlikely to spread the virus But without contact tracing to track transmission in a larger population its impossible to know if the assumption is trueWhat we know for sure is that if someone does get sick with Covid19 after vaccination in what is called a breakthrough infection symptoms will be milderStudies have found that people who tested positive for Covid19 after getting just their first vaccine dose had lower levels of virus in their bodies than unvaccinated people who tested positiveThe researchers believe the decreased viral load hints that vaccinated people who do contract the virus will be less infectious because they will have much less virus that could be spread to othersA preprint study which has not yet been peerreviewed suggests that the Moderna mRNA Covid19 vaccine can produce coronavirusfighting antibodies in the oral and nasal fluidSince thats where SARSCoV2 makes its entry antibodies in the mouth and nose should block the virus from getting into the body effectively providing sterilising immunity This would also mean vaccinated people probably wouldnt spread the virus through respiratory dropletsThese bits of evidence are promising But without more studies scientists cannot yet conclude that Covid19 vaccines really do protect against all transmissionStudies attempting to directly answer this question through contact tracing are just beginning Researchers will track Covid19 infections among vaccinated and unvaccinated volunteers and their close contactsProtection and prevention go hand in handVaccines help slow down the spread of an infectious disease by breaking the chain of infectionThose who are infected eventually have fewer and fewer unprotected people to pass the virus on to This is how a vaccine increases herd immunity susceptible and notyetimmunised people are surrounded by a herd of people who have become immune thanks to vaccination or previous infection But studies suggest that for a combination of biological and social reasons vaccination alone is unlikely to achieve herd immunity against Covid19 and fully contain the coronavirusIn fact vaccination alone can take a long time to eradicate any disease Even diseases that are nearly eliminated such as chickenpox measles and pertussis can resurface with waning immunity and declining vaccine ratesThe recent outbreak of infections among the vaccinated New York Yankees shows that vaccinated people not only can still get infected they might also transmit the coronavirus to close contactsHighly tested groups such as professional sports teams spotlight the fact that mild asymptomatic infections among the vaccinated in the general population might actually be more frequent than reportedA similar outbreak in airport workers in Singapore shows that even among the fully vaccinated new and more infectious variants can spread fast The CDCs relaxed guidelines on masking are meant to reassure vaccinated people that they are safe from serious illnessAnd they are But the picture is less clearcut for the unvaccinated who interact with them Until near herd immunity against Covid19 is achieved and clear evidence accumulates that vaccinated people do not spread the virus I and many epidemiologists believe it is better to avoid situations where there are chances to get infected Vaccination coupled with continued masking and social distancing is still an effective way to stay saferThis story has been sourced from a third party syndicated feed agencies Midday accepts no 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