The post-infection impact on health services of the SARS-Cov-2 pandemic has been the topic of several studies [10, 15–20]. Among them, we recently reported data based upon an administrative database on the consequences along the first six months after recovery from the first SARS-CoV-2 infection wave in terms of deaths, hospitalizations, attendances at hospital emergency rooms, outpatient medical visits and drug dispensation [12]. However, after this early increase the post-recovery impact on the regional healthcare facilities did progressively decrease [13]. In the present analysis of the second and third infection waves a mild impact pertained to deaths, hospitalizations and outpatients visits but the healthcare impact was important regarding to a few dispensed drugs and diagnostic tests.
Lombardy is an adequate model to study the post-infection healthcare resource utilization, because this Italian region (10 million inhabitants with a high density) was the first large area after China to be heavily hit by SARS-CoV-2 [1–3]. During the early pandemic period from March to May 2020 the total number of deaths registered in the region did increase by + 212%% in comparison with the average numbers recorded in the same months of the pre-pandemic years 2015–2019 [21]. Because scanty data are generally available on healthcare resource utilization following infection waves other than the first, we chose to evaluate 585.198 cases who did recover (315.593 after the second and 269.605 after the third wave) throughout the first six months post-negativization regarding deaths, hospitalizations, attendances at hospital emergency rooms, outpatients medical visits, dispensation of drugs and an array of imaging, instrumental and biochemical diagnostic tests. These data were compared with those obtained in the same persons before the pandemic outbreak in the corresponding months of 2019, so that each patient was his own comparator before and after the pandemic. Obviously, this comparison could not be done pertaining to deaths in the post-recovery period, but the crude mortality rates recorded after both waves were much lower than after the first wave (0.5% after the second and 0.6 after the third versus 3.9% after the first) [12].
We chose to confine our analysis to the post-infection impact of the second and third infection waves instead of directly comparing the related data with those of the first, because the epidemiological, medical and social scenarios were strikingly different regarding age, mortality, rate of hospitalisation and availability of pharmacological and non-pharmacological interventions, even though vaccination was not yet started in Lombardy at the time of the second wave and involved a small number of citizens infected during the third wave. Main findings were that after both waves hospitalizations, emergency room attendances and outpatient visits were similar or even lower than in the corresponding pre-COVID 2019 periods. Only the more compromised patients discharged from ICU, a minority in the whole cohort ranging from 0,3% to the 0,6%, needed more hospital admissions in the second and third waves than in 2019. Thus, the data reported herewith depict a scenario completely different from that of the first six months following the first dramatic wave due to the original SARS-CoV-2 lineage [12].
This scenario of relatively mild burden on the regional health service regarding pivotal events such as deaths, hospitalizations and outpatient visits is at a variance with that regarding a few dispensed drugs and diagnostic tests. A definite increase in dispensation was registered for ATC drug classes addressing the cardiorespiratory, blood and central nervous systems. In addition, diagnostic tests such as chest CT scans showed the most important increase with nearly tripled numbers, but also spirometry, electrocardiogram, echocardiography and a number of blood tests (i.e., complete blood count and coagulation tests) were performed more frequently than in 2019, particularly after the second wave.
The finding of less hospitalizations, emergency room and outpatient visits contrasting with the increased dispensation of a number of drugs classes and diagnostic tests might derive from various causes including logistic factors, health management habits by family doctors and self-medication. Another potential cause is a rebound effect after the strict lockdown and subsequent containment measures. However, a rebound effect was not actually recorded in the region, that in general witnessed a continuing low dispensation of all resources related to healthcare. In addition, the increase of drug and diagnostic test dispensation was not uniform as it would be expected in the frame of a rebound effect, but preferentially confined to drugs and tests related to organs and body systems such as the heart, lung, blood and the central nervous system, that are frequently involved in the post-infection sequelae. The important growth of CT scan and spirometry dispensation is perhaps due to the persistence over time of respiratory discomfort and other subjective symptoms, as well as to monitoring the risk of fibrotic lung evolution. The increase of blood and coagulation drugs and diagnostic tests may be linked to the post-recovery persistence of the abnormalities recorded during the acute infection, but also to the reluctant deprescribing by family doctors.
This study has the limitations of those based upon administrative databases, because data could not be audited and a number of details are not available from the database. For instance, we have no direct information on the main signs and symptoms in the post-recovery period, so that for instance the persistence of respiratory discomfort explains only hypothetically the important increase in the use of chest CT scans and spirometry. On the other hand, administrative data indeed offer an opportunity to monitor the access to pivotal health care resources of large populations, that in this study are represented by an important and densely populated European region. The epidemiology of the second and third wave were quite similar in different European regions and Lombardy mirrors this pattern [22, 23]. Other strengths of this study are the large number of cases, the real-life approach and particularly that infected cases were their own comparator owing to the availability of the corresponding data in the year before the onset of the pandemic.
In conclusion this report, describing the post- infection healthcare burden of 585.198 cases who recovered from the second and third infection waves, indicates that during the periods considered the post-COVID burden was much smaller than following the early post-recovery period after the first wave due to the original Wuhan SARS-CoV-2 lineage.