In the United States, many people have received either Pfizer or Moderna COVID-19 vaccines. These vaccines require two doses spaced one month apart. There is a period between the first dose, when the vaccine provides some degree of protection, to after the second dose when the vaccine protection is maximized. In public, this is often described as partially vaccinated v.s. fully vaccinated. The label partially vaccinated has a connotation of temporary and insufficient. I believe this is not accurate. I suggest a different set of labels, vaccinated and double vaccinated, to describe these two stages. This label could help shape public perception and health policy and improve outcome.

First of all, the maxim of biology is that nothing is ever binary. Everything is really different shades of gray. In this respect, the label fully vaccinated also has an inaccurate connotation. Rather than making you 100% safe from COVID, it should be understood as having stronger protection, not a 0 and 1 difference. Pfizer and Moderna are impressively effective vaccines. Real world data suggest just one dose of vaccine reduce the chance of inflection by 80%. This is higher than the 70% effectiveness claimed by the alternative J&J vaccine. It should not be thought of as insufficient.

How do people decide there should be two doses of vaccine spaced one month apart? Is it better or worse than spacing three months or six months apart? Why is two doses instead of one dose? Could three doses do even better? There is not really a correct answer. The way it is decided can be described as trial and error. Scientists experimented with different dosages and schedules and found one that works best. Given the compressed schedule to obtain regulatory approval, the pharma companies do not even have time to test three month or six month spacing. So one month it is. The recommendation is also a balance of cost and benefit. Let’s say a third dose provides an additional 5% protection. This is unlikely to be recommended because the benefit does not justify the cost and the burden of making three visits to a clinic.

There are different strategies to roll out vaccination besides strictly following the one month spacing. Consider 100 people and 100 vaccine doses available. We can either give every one one shot, or we can have 50 people two doses but left nothing for the other 50 people. In the first case, all 100 people have 80% protection. In the second case, 50 people have 90-95% protection, but the other 50 have none. The first case is much more preferable than the second as far as public health’s concern. UK has adopted the first strategy for its vaccine roll out. People are recommended to wait three months for the second dose in order to vaccinate more people. As a result, the COVID case in the UK has plummeted, a sharp contrast to continental Europe.

This is why I suggest to use the label vaccinated and double vaccinated to avoid the connotation of inadequately vaccinated. For public health tracking purposes, the primary metric to consider is the number of people vaccinated. The number of people who have received two doses is much less important than the first.

2021.04.25 comments

San Francisco’s COVID vaccine effort continues at a brisk pace. Today, 56% of adults have already received at least one shot of vaccine. How much longer does it take to vaccinate 80% of adults? At the current pace of 12.6k vaccination per day, it will take 15 more days. April 26th is the earliest day where everyone who wants a vaccine will get a vaccine (assuming 20% of people decline). In practice, it will take more days because some vaccines are used for second shots. Nevertheless, it is tremendously encouraging to see the progress. This schedule is ahead of even the most optimistic prediction at the beginning of the roll out.

San Francisco’s COVID vaccine effort continues at a brisk pace. Today, 56% of adults have already received at least one shot of vaccine. How much longer does it take to vaccinate 80% of adults? At the current pace of 12.6k vaccination per day, it will take 15 more days. April 26th is the earliest day where everyone who wants a vaccine will get a vaccine (assuming 20% of people decline). In practice, it will take more days because some vaccines are used for second shots. Nevertheless, it is tremendously encouraging to see the progress. This schedule is ahead of even the most optimistic prediction at the beginning of the roll out.

Therefore I am rather puzzled by the persistent reservation from a skeptic group of people. Some health experts, the media, and many concerned citizens seem to be uncomfortable with the idea that the pandemic, at least locally, is finally receding. They are nervous that the business and social restrictions will be relaxed. They raise alarm for a possible fourth wave, the threat of variants, and outbreak brought on by reopening too soon. For some reason, they tend to dismiss the vaccine success that I celebrated. The health authorities and media are reluctant. They say we don’t have enough vaccines. They say we have a supply problem.

This is misleading and false. If everyone demands vaccines today, there are not enough. But this is not what people are asking for. They just want to get in line to receive a vaccine in a predictable time frame. As I have shown, it only takes 15 more days at the earliest to vaccinate everyone who wants a vaccine. There is no supply problem I am aware of. Why do health authorities keep making caution statements that are not warranted? Why don’t they acknowledge and celebrate the success? Newsom and London Breed understand that there is a robust supply. Therefore they keep pushing the eligibility time frame more and more ahead. Why do the health authorities not see this?

Ironically, the retreat of the pandemic intimidates some people. They are used to and feel safe to remain in the isolated cocoon. It feels scary to mingle with people again.

The justification is usually that the risk remains here and we must be cautious. It is true that the assessment of the risk is subjective, with some people tend to be optimistic and some people tend to be pessimistic. Nevertheless, any reasonable argument must be constrained by objective basis. We criticized the Trump administration for denying evidence and downplaying the pandemic. In a similar manner, we should question the alarmists who make unwarranted cautions. Too little action is bad. However, excessive amounts of action are also bad. The proper action should be proportional to the risk, not too little, not too much.

Today the pandemic has not yet come to a definitive end. But, as you can see in the vaccination progress, change is coming fast. The skeptics believe they are rightly being cautious. But if they do not adjust their assessment as the situations change, this belief will quickly descend into superstition.

2021.04.11 comments