There is some evidence that those with prior infection with “natural” immunity have sustained protection for at least 12 weeks or more, so it is reasonable to hypothesize the same might be true for a single vaccine dose. For other infectious diseases, such as with many childhood vaccinations we have seen a little bit of flexibility with “catch up” immunization scheduling, but the CDC discourages excessive delay.
The European Medicines Agency has suggested that for the Pfizer-BioNTech vaccines, the second dose should not be longer than 42 days. In contrast to UK and European officials, the US FDA has strongly discouraged changing the dosing schedule, noting that such changes without data is premature. As of this writing, now 22.1 million doses have been distributed, and 6.7 million doses have actually been given to people.
It is unclear that the primary barrier to vaccine access is the availability of doses. Distributing vaccines is an enormous logistical challenge even in the best case of centralized health systems and coordination. In the US, this is made even more challenging in a large country with a heterogeneous and fractured health system. Even so, the distribution has been accelerating. There is also the other concern about uptake—even as vaccine doses get sent out, people must accept them. Even among eligible healthcare workers, a large percentage have opted not to receive the vaccines, at least not right away. This may improve with time and more and more people receive the vaccine.
Dr. Anthony Fauci, head of the infectious disease division of the NIH has cautioned against any delays or tinkering with the vaccine schedule, primarily as it could further erode public trust.
Currently, things are dire—Los Angeles County is looking at the worst-case scenario of rationing acute medical care. A new variant of the mutation has accelerated the spread of an already highly contagious virus. Despite record-breaking numbers of infections, hospitalizations, and deaths, it is likely we have not seen the worst of this surge. The spread of the virus to parts of the world with even fewer resources could be even more catastrophic than what has already occurred.
The uncomfortable truth is that public health authorities and leadership must make rapid decisions with profound consequences with limited information. They must do this with transparency and informed by the best available science and ethical considerations. That this public discourse is also heavily politicized, rife with misinformation and mistrust, complicates this.
There continues to be a long road ahead. Even so, in less than a year, a brand new infection was sequenced, and effective vaccines were delivered into the arms of people. Front line medical staff have drastically reduced the mortality rate of patients. Billions of people have cooperated, sometimes with great personal sacrifice, to slow the spread of this infection. This continues to be astonishing.
Dharushana Muthulingam, MD, MS, is an infectious disease physician and public health researcher in St. Louis.