This is the third in a series of posts about how Covid has affected different age groups in Massachusetts. As I noted in the post describing my calculation methodology (https://www.masscoronavirus.net/massachusetts-covid-breakdown-by-age-part-i-methodology/), the hospitalization information provided by the state appears unreliable. First, it does not align with hospitalization admissions provided to the state by hospitals directly (https://www.masscoronavirus.net/the-massachusetts-hospitalization-puzzle/). Second, the weekly breakdown of hospitalizations by age under counts new hospitalizations compared to the daily data provided by the state in its race / ethnicity report. So this analysis should be viewed with some skepticism – although it probably is roughly correct in a broad sense.
Figure 1 shows the rate of new hospitalizations for each age cohort, with a later start to the figure because of the higher rate of hospitalizations for the 80 plus cohort earlier in the pandemic. (At its peak, the weekly new hospitalization rate for that group was roughly 180 per 100,000). As expected given what we know about Covid, these rates sort in descending order from oldest to youngest cohort.
The number of new hospitalizations for the 80 plus group sharply declined during May (not shown) and June, falling almost 95% from the end-of-April peak by early July. The decline also occurred for the other age cohorts in May and June, but not quite as sharply. Since June, the new hospitalization rate has been relatively stable regardless of age – the recent uptick in hospitalizations from the data provided by hospitals is not yet evident in these state-provided data by the beginning of October.
One other point. Since June 1 approximately 70% of reported deaths in Massachusetts have been residents of long-term care facilities. Many of these ill long-term care residents are never admitted to the hospital, and the bulk of them are 80 and over (and the overwhelming majority are 60 and over). Thus, any measure of illness that looks at hospitalizations to cases will likely underestimate the severity of Covid, particularly in the senior population.
Figure 2 shows the percentages of new hospitalizations by age cohort. It is difficult to discern meaningful patterns here (perhaps a result of the unreliability of the data). Younger seniors (60 to 79) have tended to be hospitalized the most. However, there are about 4 1/2 times more people in Massachusetts between 60 and 79 than there are 80 and over. While about 15% of hospitalizations have been for people 40 and under since the end of June, they are over half the population of Massachusetts. Still, this is perhaps a higher percentage than one might expect (and flies in the face of some of the folk wisdom about Covid).
Figure 3 shows the ratio of new hospitalizations to population for each age cohort. This clearly shows the relative extent to which seniors have become hospitalized from Covid, particularly those 80 and up. (The dip in the percentages for those 80 and older for about a month from mid-August to mid-September is probably an artifact of the unreliability of the data and my calculation approach). Most surprising to me is the 40 to 59 year old age group, for which new hospitalizations almost track their population share, particularly in the last month. I would have expected this percentage to be lower.