Adventures of a self-learning data scientist - Do some municipalities have superfluous stocks of Pfizer vaccines?

Reference materials in this post are all in Japanese:

The central government says that it distributed 88 million shots vaccines to municipalities by the end of June, the reported shots are 48M shots, so there are 40M shots stocks, and some municipalities must have superfluous stocks.

Municipalities say they don’t have any superfluous stocks, and some of them stopped taking reservations for shots.

FNN reports that 40M shots stocks are 25M reserved for the second boost shots, 5M not-yet-reported shots, and 10M missing for unknown reasons.

According to “Prospects for Pfizer vaccine supplies” by Ministry of Health, Labour and Welfare, MHLW planned to distribute 68,341 boxes to municipalities. One box contains 195 vials. One vials contain 5 or 6 shots, according to the injector type.

68,341 boxes can be 67M - 80M shots, but can’t reach 88M shots. At least 8M shots were not delivered to municipalities, if “Prospects for Pfizer vaccine supplies” by MHLW is correct.

MHLW distributes 21,600 boxes in July, and the officer of the Cabinet Office says the government distributes 25M shots in July. 21,600 boxes can be 21M - 25M shots. Looks like the officer assumes 6 shots per vial. Is this assumption practical?

According to Pfizer manual, after the vial is diluted, it must be shot in 6 hours. At the end of the day, each center or clinic will try to exhaust the last diluted vial, but it will fail to do so at some probability.

Imagine that the expected shot loss from the last diluted vial is 0.2 shots (four cases of 1 shot unused, three cases of 2 shots unused, two case of 3 shots unused and one case of 4 shots unused out of 100 last diluted vials).

And imagine the only one center tries to do 1.2M shots per day (37M shots per month) in July. Then the number of the last diluted vial is one per day, and the expected shot loss is 0.2 shots per day (6.2 shots per month).

Instead, imagine 55 thousand clinics are scheduled to do 1.2M shots per day (37M shots per month) in July, as the officer says. Then the number of the last diluted vial is 55K per day, and the expected shot loss is 55K * 0.2 = 11K shots per day (341K shots per month).

Thus, some of missing vaccines may be due to shot losses at the last diluted vial.

More centralized regime leads to less shot losses. The decentralized regime may have facilitated 65 years or older people to get shots at nearby clinics. However, the centralized regime may be more desirable now, as younger generations get shots.

I am scheduled to get the first shot of Pfizer vaccine at the municipal center on August 2.

--- title: 'Do some municipalities have superfluous stocks of Pfizer vaccines? ' author: Mitsuo Shiota date: '2021-07-17' categories: - economics --- Reference materials in this post are all in Japanese: - [FNN Prime Online: Missing 40M shots vaccines](https://www.fnn.jp/articles/-/211144) - [CNET Japan: Gov't provides an IT system to support 1.2M shots per day](https://japan.cnet.com/article/35174047/) - [Ministry of Health, Labour and Welfare: Prospects for Pfizer vaccine supplies](https://www.mhlw.go.jp/stf/seisakunitsuite/bunya/vaccine_supply.html) - [Pfizer: Handling manual of Pfizer vaccine](https://www.pfizer-covid19-vaccine.jp/%E3%83%AF%E3%82%AF%E3%83%81%E3%83%B3%E3%81%AE%E5%8F%96%E3%82%8A%E6%89%B1%E3%81%84.pdf) The central government says that it distributed 88 million shots vaccines to municipalities by the end of June, the reported shots are 48M shots, so there are 40M shots stocks, and some municipalities must have superfluous stocks. Municipalities say they don't have any superfluous stocks, and some of them stopped taking reservations for shots. FNN reports that 40M shots stocks are 25M reserved for the second boost shots, 5M not-yet-reported shots, and 10M missing for unknown reasons. According to "Prospects for Pfizer vaccine supplies" by Ministry of Health, Labour and Welfare, MHLW planned to distribute 68,341 boxes to municipalities. One box contains 195 vials. One vials contain 5 or 6 shots, according to the injector type. 68,341 boxes can be 67M - 80M shots, but can't reach 88M shots. At least 8M shots were not delivered to municipalities, if "Prospects for Pfizer vaccine supplies" by MHLW is correct. MHLW distributes 21,600 boxes in July, and the officer of the Cabinet Office says the government distributes 25M shots in July. 21,600 boxes can be 21M - 25M shots. Looks like the officer assumes 6 shots per vial. Is this assumption practical? According to Pfizer manual, after the vial is diluted, it must be shot in 6 hours. At the end of the day, each center or clinic will try to exhaust the last diluted vial, but it will fail to do so at some probability. Imagine that the expected shot loss from the last diluted vial is 0.2 shots (four cases of 1 shot unused, three cases of 2 shots unused, two case of 3 shots unused and one case of 4 shots unused out of 100 last diluted vials). And imagine the only one center tries to do 1.2M shots per day (37M shots per month) in July. Then the number of the last diluted vial is one per day, and the expected shot loss is 0.2 shots per day (6.2 shots per month). Instead, imagine 55 thousand clinics are scheduled to do 1.2M shots per day (37M shots per month) in July, as the officer says. Then the number of the last diluted vial is 55K per day, and the expected shot loss is 55K * 0.2 = 11K shots per day (341K shots per month). Thus, some of missing vaccines may be due to shot losses at the last diluted vial. More centralized regime leads to less shot losses. The decentralized regime may have facilitated 65 years or older people to get shots at nearby clinics. However, the centralized regime may be more desirable now, as younger generations get shots. I am scheduled to get the first shot of Pfizer vaccine at the municipal center on August 2.