While there is still much more information to gather about the Delta variant of the coronavirus pandemic, there are several things we do know. The first fact is that the Delta variant is more contagious than any other virus strain, the first Delta case was identified in December of 2020, and by the end of July, the Delta variant has become the cause of more than 80 percent of new COVID-19 cases in the United States.
The second fact is that people who have not been vaccinated are most at risk of being infected by the Delta variant. In some states where vaccination rates are low, the number of coronavirus cases is increasing. Scientists are also in constant pursuit of answering questions about the variant, such as how the Delta variant will affect the body and whether booster shots for vaccines are necessary to protect individuals against the dominant strain. To answer both questions, many scientists have been learning more about the Delta variant and the possibility of breakthrough infections.
CDC studies regarding breakthrough COVID-19 infections
Federal health authorities have discovered new data that notes mild to moderate breakthrough infections among people who received the messenger RNA vaccine Pfizer and Moderna shots. The longer it has been since the individual received their vaccinations, the more common it can become for a breakthrough infection to occur.
According to health authorities, this occurrence is known as “waning” immunity, and is the main reason why authorities recommend that a booster shot be administered for individuals who received their second shot eight months ago. Federal health authorities came to this conclusion after three studies from the Centers for Disease Control and Prevention (CDC). These three studies helped to provide additional insight into how the Pfizer and Moderna vaccines protected against infection and hospitalization.
Results from the first study by the CDC
The first study reported from the CDC consisted of a large study among nursing home residents. The results from the study concluded that as the Delta variant grew more dominant, the vaccine efficacy against infection waned. Prior to the Delta variant, both vaccines were capable of providing 74.7 percent protection against infection for the nursing home demographic. After the Delta variant, however, vaccines were able to provide protection against infection for 53.1 percent of the time.
Results from the second study by the CDC
For the second study, researchers decided to cross-reference databases with hospitalizations and vaccination status in New York City. The results from this study determined that around the same time that the Delta variant came into dominance, vaccine efficacy against infection decreased from 91.7 percent to 79.8 percent. As far as hospitalization is concerned, vaccine efficacy against severe disease remained relatively stable.
Results from the third study by the CDC
The third study consisted of a multi-state study that looked at more than 1,100 patients over the time span of 24 weeks. The results determined that there was no decline in vaccine effectiveness against COVID-19 hospitalization. The results did discover, however, that vaccine efficacy was lower in people with weakened immune systems.
Conclusions from all three studies
The results from all three studies indicate that vaccine efficacy against infection declined while protection against severe disease requiring hospitalization remained high. Right now, 51 percent of all Americans are fully vaccinated, and although the vast majority of patients that are hospitalized are unvaccinated, the deaths among the fully vaccinated are effectively zero. Even though the data affirms that vaccine protection remains high against hospitalization, health officials are warning that immunity could wane in the future, and administering booster shots can help to stay ahead of the virus.
Do scientists think we need booster shots?
Although many scientists predicted that booster shots would be necessary, some question whether the data supports their immediate distribution. One concern with the data presented is that the data did not show whether a pattern of waning immunity for mild and moderate disease will certainly translate to waning immunity against hospitalization and death. Although some scientists do believe that the decreased vaccine effectiveness for mild to moderate disease can extend to moderate to severe disease, this is purely an assumption; no evidence has been presented to support this theory so far.
Federal health authorities have also presented evidence that antibody levels increase significantly after a booster shot. However, there is still an uncertainty as to how long the heightened immunity will last. This uncertainty has spawned concern that the increased protection against mild to moderate disease may only be temporary and the resources it would take to administer booster shots may not be worth the effort.
What should I do now?
Vaccines are normally reviewed by multiple independent scientific panels, and before the booster shots are rolled out in September, both the Pfizer and Moderna vaccines will be reviewed again by the Food and Drug Administration (FDA) and a CDC advisory panel. As far as eligibility is concerned, people with moderately to severely weakened immune systems are already eligible for a third mRNA vaccine shot. At the very least, anyone who has not already been vaccinated should do so, as it is the best way to protect themselves and the people around them from COVID-19 infection.
The best practices for reducing potential virus exposure involve the old-fashioned methods everyone has been accustomed to since the beginning of the coronavirus pandemic: masking, social distancing, and hand-washing. This is especially important for children under the age of 12, as they are not yet eligible for the vaccine.