According to CDC (Centers for Disease Control and Preventions): Vaccine breakthrough cases may reduce public confidence in vaccines:

Vaccine breakthrough cases are expected and increase as a proportion of total cases as vaccine coverage increases. Vaccine breakthrough cases will occur more frequently in congregate settings, and in groups at risk of primary vaccine failure (i.e., immune compromised, elderly, etc.).

Communication challenges have been associated with increasing proportions of cases vaccinated even when vaccine effectiveness (VE) remains stable: 

• Concerns from local health departments about vaccine effectiveness (VE)
• Public convinced vaccines no longer work/booster doses needed
• Important to update communications describing breakthrough cases as “rare” or as a “small percentage” of cases

 

Early evidence in health care providers that vaccination may reduce transmission and attenuate illness (HEROES/RECOVER)

During the period December 14, 2020 to April 10, 2021, vaccine effectiveness (VE) against infection was 91% among fully vaccinated; 81% for partially vaccinated. Compared to unvaccinated persons, vaccinated persons (full or partial) had:

• 40% lower mean RNA viral load
• shorter mean duration of detectable viral RNA
• lower risk of febrile symptoms
• shorter mean duration of symptoms

 

In Summary:

Delta variant is different from previous strains: it’s highly contagious, likely more severe and is very deadly and harmful, especially to unvaccinated individuals. In order to prevent contamination, all individuals must pay attention, adhere to putting masks and keep social distancing until they receive the vaccine in both doses, and thus the body becomes immune to the virus. The public must understand that breakthrough infections risk of severe disease or death is reduced 10-fold or greater if vaccinated, and risk of infection is reduced 3-fold if vaccinated.