Of the 100 reported deaths, the expert group classified 10 (10 %) as most likely related to the vaccine, and considered that there could be a possible link for 26 (26 %). It must be emphasised that these estimates are very uncertain, which is illustrated by the moderate kappa values for agreement between the initial assessments.
The spontaneous reporting system for adverse drug reactions is primarily useful for generating hypotheses and is not particularly suitable as a basis for assessing causality. Many of the reports did not contain sufficient clinical information to form an impression of the patient's clinical course and a possible causal link between vaccination and death. Almost half of the reporting parties did not submit additional information. In particular, there was a lack of information about which phase of life the patients were in, and whether their health and general condition were already rapidly or slowly deteriorating before vaccination. All patients were in a complex clinical situation characterised by old age, frailty and multiple chronic diseases, which means that a variety of factors could have contributed to the deaths. It is therefore practically impossible to determine with any certainty how much of a role the vaccine played in the deaths.
The extremely high mortality rate in nursing homes means that random factors will lead to a certain number of deaths shortly after vaccination anyway. It cannot be ruled out that some of the deaths that were classified as probable are in fact due to such random factors. Nevertheless, we find it reasonable to assume that adverse effects from the vaccine in very frail patients can trigger a cascade of new complications which, in the worst case, end up expediting death.
The categories 'probable' and 'unlikely' were used in cases where the expert group considered there to be a clear likelihood one way or the other, and the category 'possible' was used where a causal link between vaccination and death was just as likely as unlikely. Many of the cases classified as 'possible' are therefore very uncertain, and some of them could perhaps also have been categorised as unclassifiable. The group considered far more cases to be either probable or unlikely than the Norwegian Institute of Public Health in its initial assessment. This is probably due to access to more information as well as knowledge of typical clinical courses in frail elderly people.
The adverse reaction reports were submitted within a period of approximately 50 days, during which it can be assumed that 2000–2500 nursing home patients died in Norway
(7). Whether 10 or 36 of these deaths were accelerated by the vaccine, the proportion is still low. In the same period, almost 30 000 nursing home patients were vaccinated, which means that there will most likely have been far more than 100 deaths in nursing homes in a close temporal relationship to vaccination in the relevant time period. Our findings cannot therefore be used to estimate the incidence of vaccine-related deaths.
It is important to emphasise that the vast majority of long-term patients in nursing homes have a short remaining life expectancy. They are definitely in the final stage of life. This is reflected in the expert group's scoring of 48 out of 79 classifiable patients in CFS category 8 or 9, which indicates an expected lifespan of less than six months. This has two important implications. The first is that the task of the expert group in practice was to identify a possible acceleration of an already rapidly deteriorating clinical course, which is schematically outlined in Figure 1. Such an assessment requires nuanced and detailed clinical information, which in many cases was not available. The estimates are therefore uncertain. The second implication is that even in cases where the causal link was classified as probable, death may have occurred only a little sooner (days, weeks or a few months) than would otherwise have been expected. This is an important aspect to consider. Also in these cases, vaccination was in all probability only a contributing factor to the cause of death. The patient's frailty, comorbidity and age were also necessary links in the causal chain.
Figure 1 Theoretical link between the death process and vaccination, heavily schematised. The X-axis illustrates the time and the Y-axis illustrates the remaining life expectancy. a) Vaccination did not hasten death. b) Vaccination accelerated death.
Our findings should not be interpreted as implying that patients with a CFS score of 8 should not generally be vaccinated. Frail patients can potentially benefit considerably from vaccination because of the high mortality rate from COVID-19
(13) among this group, a high risk of long-term effects on function and quality of life (14) and the benefit from eased visiting restrictions.
Frailty assessments can, however, be used to identify patients who are particularly vulnerable to adverse drug reactions and probably also adverse reactions to the vaccine. It is reasonable to assume that the risk of fatal consequences from adverse effects of the vaccine can be reduced through preventive measures such as sufficient hydration, medication review and optimised treatment of comorbid conditions. Clinical vigilance for acute functional failure, for example due to an intercurrent infection around the scheduled time of vaccination, is also likely to be important, so that vaccination can be delayed if necessary. For those with the most impaired physiological reserves, the advantages and disadvantages of vaccination must be carefully considered. It is our view that this is adequately discussed in the current version of the Norwegian Institute of Public Health's COVID-19 vaccine guide