It has been expected, but now it has happened. Following in footsteps of Canada a week before, the United States Food and Drug Administration (FDA) has extended the emergency use authorization (EUA) for the Pfizer-BioNtech vaccine against SARS-CoV2 (the virus that causes COVID-19) from a previous minimum age of 16 years down to the age of 12 years. My children —ages 14 and 12— and many of your children too, are now eligible for vaccination, so the next steps will involve appointments becoming available at various locations in all US states and in many cases the school systems getting involved to help organize specific days for students to have appointments at vaccination facilities.
As emphasized in my previous article, it is very important to get your children vaccinated ASAP, for a few reasons: First, SARS-CoV2 infection in children can lead to severe disease, although much more rarely compared with adults, but children can spread the virus to vaccine-hesitant adults. Moreover, to get the pandemic under control, we need to get a lot of people vaccinated. It comes down to a numbers game related to the capability of the virus to spread, and so to compensate for the numerous anti-vaxxer adults and the adults who are hesitating because they believe, mistakenly, that the vaccines are risky and want other people to take the risks in their stead, millions of children, beginning with the young teens, are standing by ready to step up to the plate. Vaccination is a community thing. They are a component of public health, emphasis on the word public. Like agreeing to turn off the lights and use blackout curtains in your home during an air raid in London in World War II, the argument about contributing to the protection of the community must be balanced against the argument about your personal freedoms.
If you have been reading what we have been posting here on The Pulse about a variable used in epidemiology called the R0 (pronounced R naught), it will seem very straightforward. R0 represents the average number of people that an already-infected individual infects. If R0 equals 1, then each infected person infects just one other person, which means that that the number of cases does not increase over time. If R0 equals 2, then each infected person infects two other people, so the number of infected people doubles over the average amount of time that the infection takes to spread from person to person, and the number of cases doubles over an amount of time that depends both on how long it takes for the infection to spread from person to person and how long it takes for people to become symptomatic.
In the case of SARS-CoV2, the R0 is now thought to be in the range of 2.5 to 4, with the more infectious variants being closer to 4 than 2.5. Maybe, some variants are emerging with an R0 higher than 4, for instance approaching 5, but let’s use an R0 of 4.0 here. In order to get control over the pandemic, we need herd immunity, which means having a certain minimum fraction of people immune, either through vaccination or previous infection with the virus to prevent the virus from increasing its prevalence in the community. That needed fraction depends on the R0 and there is an equation for calculating it. You take the reciprocal of the R0, meaning 1 divided by the R0, and then you subtract that number from 1. Thus, for a variant of SARS-CoV2 whose R0 equals 4.0, we divide 1 by 4, which gives us 0.25, then we subtract 0.25 from 1, which gives us 0.75, or 75 percent, meaning that for herd immunity we need a minimum of 75 percent of all people who are in interacting community to be immunized, either through vaccination or having been infected with the virus. Now, certainly there are places with higher fractions of the population being vaccine hesitant or anti-vaxx and other places where people are more compliant about getting their vaccines, but overall, we are talking about 75 percent, and experts think we should consider 80 percent as the target, because of new variants that may have an R0 closer to 5.0 (1/5 = 0.2; 1-0.2 = 0.8). Except in places where nearly all of the adults get vaccinated, we cannot get to 75 percent or 80 percent of people, if the children are not vaccinated too. And so there is a direct connection between the vaccine hesitancy among adults and the need for COVID-19 vaccination to be expanded to children.
As noted above, the new EUA extension making COCID-19 vaccination available to children ages 12 and up is for the Pfizer-BioNtech vaccine, but additional EUA extensions down to age 12 also are anticipated for Moderna and Janssen (Johnson and Johnson). Meanwhile, the Novavax vaccine may receive an EUA covering adults very soon, with lower ages to follow and clinical trials are in progress for COVID-19 vaccines in children ages 11 years down to 6 months.