Moderna stated Thursday that the highly contagious delta variant could lead to an increase of breakthrough infections in fully vaccinated people as they move indoors after the summer.Moderna's two dose vaccine is still "durable" six-months after the second shot. However, immunity to the coronavirus will continue waning and eventually affect vaccine efficacy, according to slides included with its second quarter earnings report.According to the company, its vaccine is 93% efficient six months after the second dose. Pfizer and BioNTech, however, claimed that their vaccine efficacy dropped to 84% six months after the second dose.Moderna stated, "Given the intersection, we believe dose three booster will likely need prior to winter season."Moderna's warning comes as the disease continues to spread in over 100 countries, including the United States. According to the Centers for Disease Control and Prevention, Delta, which is the most common form of the disease, is more easily transmissible than smallpox and Ebola.Some Americans are more concerned about vaccine efficacy than ever due to the rapid spread of the variant. This variant may cause more severe diseases than the original coronavirus. Some have even sought out a supplemental dose of vaccine, something that is not recommended by CDC. San Francisco health officials announced this week that they will allow patients who have received Johnson & Johnson's vaccine to receive a second shot by Moderna or Pfizer BioNTech.For months, drug companies have stated that they believe people will eventually require booster shots and possibly additional doses each year. This is similar to the seasonal flu.Moderna announced Thursday that results from phase 2 of its vaccine trial showed that a booster dose produced an "excellent" antibody response to three variants of the vaccine, including delta.According to the CDC and World Health Organization, booster doses are not necessary at the moment due to lack of data. The WHO called wealthy countries to stop distributing Covid booster shots Wednesday to allow the world to reach the director-general's goal to vaccinate 10% of all people by September 31st.At a press conference, Tedros Adhanom Gebreyesus, WHO Director General, stated that "we need an urgent reversal" from vaccines being sent to most high-income countries to those going to the majority to low-income countries.This move follows Israel's announcement that it would offer booster doses for its elderly population. The Dominican Republic also administers booster doses to its citizens, while neighbouring Haiti just received its first dose of vaccines.Americans are looking for ways to get booster shots.Rich Mendez, CNBC, contributed to this report.
