Vaccines by Moderna, Pfizer, and AstraZeneca continue to make progress in their phase 3 trials. Pfizer-BioNTech reported that they will know by mid-October to early November the results of their trial and that they have expanded the trial to include more risky patients (i.e elderly, teenagers, and those with HIV). Moderna also reported that the results of their trial should come in November. Many people have been vaccinated in these trials and now the companies have to wait to see who gets infected. The hope is that those in the placebo group will get the illness, while those in the vaccine group will not. If at least twice as many people in the placebo group get infected vs. the vaccine group (50% efficacy), we have a winner. From the preliminary data, where the companies measured the strength of the immune response, I expect these vaccines to be much better than 50% effective. I would not be shocked by 70 to 80% effectiveness.
Why isn't it 100%? The vaccine depends on the human immune system raising an immune response against the virus. In some cases, due to age or other conditions, this doesn't happen and that individual is not protected. Another factor is the amount of SARS-CoV-2 a person is exposed to when they do get infected. The higher the dose, the more likely they will be to get the disease. Another key element to watch for is the severity of the illness in the vaccinated cohort vs the control. If the disease is milder in the vaccine group, that is yet another reason to get vaccinated. Even at 50% efficacy, if enough people get vaccinated, it will greatly hinder the spread of the virus and bring the pandemic to an end.
In a clever bit of work, University of Pittsburgh Scientists may have developed a powerful treatment against COVID-19. A "fishing pole" that used the S protein of the SARS-CoV-2 virus as bait was used to tease out molecules that bound to it tightly. The method was simple enough that the scientists, lead by Dimiter Dimitrov, were able to screen 100 billion candidates. The most promising, Ab8, is part of the variable region of the heavy chain of an antibody. By attaching immune signaling components to Ab8 a streamlined, and much smaller, signaling molecule was created that will alert the immune system to the presence of SARS-CoV-2 and lead to its destructions. Ab8 was found to prevent infection in mice and hamsters. The drug is expected to quickly go into clinical trials with humans.