Natural and vaccine-induced immunity are equivalent for the protection against SARS-CoV-2 infection.

OBJECTIVES: To compare the long-term cumulative risk of SARS-CoV-2 infection associated with natural and vaccine-induced immunity. METHODS: Retrospective population-based cohort study based on registry of COVID-19 vaccinations and SARS-CoV-2 infections among 9.1 million citizens of Lombardy, Italy, eligible for vaccination on 27th December 2020. Those who developed SARS-CoV-2 infection from 24th May to 14th September 2021, provided they did not yet receive the COVID-19 vaccine when infection was confirmed, and those who received the second mRNA vaccine dose, provided they had not yet developed the infection, were selected to be 1:1 matched for sex, age and index date. The latter corresponded to 90 days after confirmed infection or 14 days after vaccine administration. A control cohort including citizens who, on the index date, had neither developed infection nor received vaccination was also selected. Kaplan-Meier curves were used for comparing the cumulative incidence of new SARS-CoV-2 infection from the index date until 22nd June 2022. RESULTS: Overall, 19,418 1:1:1 risk-sets were included. After 9 months of follow-up, the cumulative risk of new SARS-CoV-2 infection was 21.8%, 22.0%, and 25.9%, respectively, among exposed to natural immunity, vaccine-induced immunity and unexposed. CONCLUSIONS: Equivalent potential for protecting against new SARS-CoV-2 infection was observed.

Developing a comorbidity score in cancer patients using healthcare utilization databases during the COVID-19 pandemic: An experience from Italy.

BACKGROUND: A strong relationship has been observed between comorbidities and the risk of severe/fatal COVID-19 manifestations, but no score is available to evaluate their association in cancer patients. To make up for this lacuna, we aimed to develop a comorbidity score for cancer patients, based on the Lombardy Region healthcare databases. METHODS: We used hospital discharge records to identify patients with a new diagnosis of solid cancer between February and December 2019; 61 comorbidities were retrieved within 2 years before cancer diagnosis. This cohort was split into training and validation sets. In the training set, we used a LASSO-logistic model to identify comorbidities associated with the risk of developing a severe/fatal form of COVID-19 during the first pandemic wave (March-May 2020). We used a logistic model to estimate comorbidity score weights and then we divided the score into five classes (<=-1, 0, 1, 2-4, >=5). In the validation set, we assessed score performance by areas under the receiver operating characteristic curve (AUC) and calibration plots. We repeated the process on second pandemic wave (October-December 2020) data. RESULTS: We identified 55,425 patients with an incident solid cancer. We selected 21 comorbidities as independent predictors. The first four score classes showed similar probability of experiencing the outcome (0.2% to 0.5%), while the last showed a probability equal to 5.8%. The score performed well in both the first and second pandemic waves: AUC 0.85 and 0.82, respectively. Our results were robust for major cancer sites too (i.e., colorectal, lung, female breast, and prostate). CONCLUSIONS: We developed a high performance comorbidity score for cancer patients and COVID-19. Being based on administrative databases, this score will be useful for adjusting for comorbidity confounding in epidemiological studies on COVID-19 and cancer impact.

Impact of the First and Second Lockdown for COVID-19 Pandemic on Preterm Birth, Low Birth Weight, Stillbirth, Mode of Labor, and of Delivery in Lombardy, Italy.

We investigated the effect of lockdown measures implemented in Lombardy on selected obstetric and perinatal outcomes. Births that occurred during the two lockdowns imposed (i.e., the first from 16 March to 2 June 2020 and the second from 3 November 2020 to 5 April 2021) and the comparison periods (i.e., the first from 16 March to 2 June 2018 and the second from 3 November 2018 to 5 April 2019) were identified using regional healthcare databases. The distribution of births according to the selected outcomes was computed and the Chi-square test was used for testing differences in the periods compared. During the two lockdowns, we observed a lower proportion of low birth weight, from 6.8% in the comparison period to 6.1% in the first lockdown (p = 0.019), and from 6.5% to 6.1% in the second one (p = 0.109). The proportion of preterm births decreased from 6.8% to 6.3% in the first lockdown (p = 0.097), and from 6.2% to 6.0% in the second one (p = 0.172). No differences in stillbirth rate emerged for both lockdowns. Induction of labor was more frequent during both lockdowns, from 28.6% to 32.7% in the first (p < 0.0001), and from 29.9% to 33.2% in the second one (p < 0.0001). Cesarean section was less frequent during the second lockdown.

Increased risk of myocarditis and pericarditis and reduced likelihood of severe clinical outcomes associated with COVID-19 vaccination: a cohort study in Lombardy, Italy.

INTRODUCTION: We aimed to assess harms (post-vaccine myocarditis and pericarditis) and benefits (preventing severe disease) of COVID-19 vaccination. METHODS: We conducted a population-based retrospective cohort study. Using the integrated platform of the vaccination campaign of Lombardy Region (Italy), after the exclusion of 24,188 individuals not beneficiaries of the Regional Health Service, 9,184,146 citizens candidates to vaccine at December 27, 2020 were followed until November 30, 2021 (the loss to follow-up rate was 0.5%). From the date of administration of each vaccine dose to day 28 post-administration, three periods that covered exposure to the first, second, and third dose were defined. The benefit-risk profile of vaccines was performed by comparing the number needed to harm (NNH) and number needed to treat (NNT) by sex, age, and vaccine type. RESULTS: Incidence rates of myocarditis were 9.9 and 5.2 per million person-months during the exposure and no-exposure periods, respectively, and the incidence rates of pericarditis were 19.5 and 15.9 per million person-months, respectively. The risk of myocarditis was highest following exposure to the second dose of the Moderna vaccine (adjusted HR: 5.5, 95% CI: 3.7 to 8.1). Exposure to the Moderna vaccine was also associated with an increased risk of pericarditis (adjusted HR 2.2, 1.5 to 3.1). NNT was higher than NNH (9471 vs. 7213) for 16 to 19-year-old men who received the Moderna vaccine, while all other sex, age, and vaccine subgroups had a favourable harm-benefit profile. CONCLUSIONS: Men 16 to 19 years of age has the highest rates of myocarditis within a few days after receiving the Moderna vaccines. The balance between harms and benefits was almost always in favour of vaccination.

Impact of COVID-19 containment measures on antibiotic prescribing for respiratory and ear diseases in pediatric primary care.

BACKGROUND: In Italy, the antibiotic prescription rate for children is very high. The aim of this study is to evaluate the change in the monthly rate of antibiotic prescriptions for respiratory and ear infections among children during the COVID-19 pandemic. METHODS: This retrospective study included all children aged <14 years who referred to a pediatric primary care clinic in Milan (Italy) between January 1, 2019, and April 30, 2022. We examined the trends in the antibiotic prescription rate, comparing the pre-lockdown (2019), total lockdown (March-April 2020), partial lockdown (November-December 2020) and post-lockdown (November-December 2021 and March-April 2022) periods. RESULTS: A total of 12 569 visits (mean age of patients: 6.3±3.8 years), with 3228 antibiotic prescriptions, were included in the study. The overall antibiotic prescription rate was 25.7%, with a nadir (5.8%) in May 2020. Compared to 2019, the highest reduction in antibiotic prescription rate was found in February 2021 (-30.3% [95% CI, -36.2%, -24.4%]). A significant increase in the antibiotic prescription rate was observed in November-December 2021 and in March-April 2022 compared to the corresponding periods of the previous year (P<0.001). CONCLUSIONS: This study showed a drastic decrease in the antibiotic prescription rate for respiratory and ear infections during the COVID-19 pandemic, with a nadir immediately after the total lockdown. Day care center and school attendance did not reverse this positive trend during the partial lockdown, unlike what happened with the relaxation of restrictive measures and the resumption of social activities after the lockdown.

Factors associated with severe or fatal clinical manifestations of SARS-CoV-2 infection after receiving the third dose of vaccine.

BACKGROUND: Little is known about vulnerability to severe COVID-19 illness after vaccination completion with three doses of vaccine against COVID-19. OBJECTIVES: To identify individual features associated with increased risk of severe clinical manifestation of SARS-CoV-2 infections after receiving the third dose of vaccine against COVID-19. METHODS: We performed a nested case-control study based on 3,360,116 citizens from Lombardy, Italy, aged 12 years or older who received the third dose of vaccine against COVID-19 from 20 September through 31 December 2021. Individuals were followed from 14 days after vaccination completion until the occurrence of severe COVID-19 illness, death unrelated to COVID-19, emigration or 15 March 2022. For each case, controls were randomly selected to be 1:10 matched for the date of vaccination completion and municipality of residence. The association between candidate predictors and outcome was assessed through multivariable conditional logistic regression models. RESULTS: During 12,538,330 person-months of follow-up, 5171 cases of severe illness occurred. As age increased, a trend towards increasing odds of severe illness was observed. Male gender was a significant risk factor. As the number of contacts with the Regional Health Service increased, a trend towards increasing odds of severe illness was observed. Having had a previous SARS-CoV-2 infection was a significant protective factor. Having received the Moderna vaccine significantly decreased the odds of severe illness. Significant higher odds were associated with 42 diseases/conditions. Odds ratios ranged from 1.23 (diseases of the musculoskeletal system) to 5.00 (autoimmune disease). CONCLUSIONS: This study provides useful insights for establishing priority in fourth-dose vaccination programs.

Vulnerability Predictors of Post-Vaccine SARS-CoV-2 Infection and Disease-Empirical Evidence from a Large Population-Based Italian Platform.

We aimed to identify individual features associated with increased risk of post-vaccine SARS-CoV-2 infection and severe COVID-19 illness. We performed a nested case-control study based on 5,350,295 citizens from Lombardy, Italy, aged ≥ 12 years who received a complete anti-COVID-19 vaccination from 17 January 2021 to 31 July 2021, and followed from 14 days after vaccine completion to 11 November 2021. Overall, 17,996 infections and 3023 severe illness cases occurred. For each case, controls were 1:1 (infection cases) or 1:10 (severe illness cases) matched for municipality of residence and date of vaccination completion. The association between selected predictors (sex, age, previous occurrence of SARS-CoV-2 infection, type of vaccine received, number of previous contacts with the Regional Health Service (RHS), and the presence of 59 diseases) and outcomes was assessed by using multivariable conditional logistic regression models. Sex, age, previous SARS-CoV-2 infection, type of vaccine and number of contacts with the RHS were associated with the risk of infection and severe illness. Moreover, higher odds of infection and severe illness were significantly associated with 14 and 34 diseases, respectively, among those investigated. These results can be helpful to clinicians and policy makers for prioritizing interventions.

Persistence of protection against SARS-CoV-2 clinical outcomes up to 9 months since vaccine completion: a retrospective observational analysis in Lombardy, Italy.

BACKGROUND: Scarce information is available on the duration of the protective effect of COVID-19 vaccination against the risk of SARS-CoV-2 infection and its severe clinical consequences. We investigated the effect of time since vaccine completion on the SARS-CoV-2 infection and its severe forms. METHODS: In this retrospective observational analysis using the vaccination campaign integrated platform of the Italian region of Lombardy, 5 351 085 individuals aged 12 years or older who received complete vaccination from Jan 17 to July 31, 2021, were followed up from 14 days after vaccine completion until Oct 20, 2021. Changes over time in outcome rates (ie, SARS-CoV-2 infection and severe illness among vaccinated individuals) were analysed with age-period-cohort models. Trends in vaccine effectiveness (ie, outcomes comparison in vaccinated and unvaccinated individuals) were also measured. FINDINGS: Overall, 14 140 infections and 2450 severe illnesses were documented, corresponding to incidence rates of 6·7 (95% CI 6·6-6·8) and 1·2 (1·1-1·2) cases per 10 000 person-months, respectively. From the first to the ninth month since vaccine completion, rates increased from 4·6 to 10·2 infections, and from 1·0 to 1·7 severe illnesses every 10 000 person-months. These figures correspond to relative reduction of vaccine effectiveness of 54·9% (95% CI 48·3-60·6) for infection and of 40·0% (16·2-57·0) for severe illness. The increasing infection rate was greater for individuals aged 60 years or older who received adenovirus-vectored vaccines (from 4·0 to 23·5 cases every 10 000 person-months). The increasing severe illness rates were similar for individuals receiving mRNA-based vaccines (from 1·1 to 1·5 every 10 000 person-months) and adenovirus-vectored vaccines (from 0·5 to 0·9 every 10 000 person-months). INTERPRETATION: Although the risk of infection after vaccination, and even more of severe illness, remains low, the gradual increase in clinical outcomes related to SARS-CoV-2 infection suggests that the booster campaign should be accelerated and that social and individual protection measures against COVID-19 spread should not be abandoned. FUNDING: None.

Balancing Benefits and Harms of COVID-19 Vaccines: Lessons from the Ongoing Mass Vaccination Campaign in Lombardy, Italy.

Background. Limited evidence exists on the balance between the benefits and harms of the COVID-19 vaccines. The aim of this study is to compare the benefits and safety of mRNA-based (Pfizer-BioNTech and Moderna) and adenovirus-vectored (Oxford-AstraZeneca) vaccines in subpopulations defined by age and sex. Methods. All citizens who are newly vaccinated from 27 December 2020 to 3 May 2021 are matched to unvaccinated controls according to age, sex, and vaccination date. Study outcomes include the events that are expected to be avoided by vaccination (i.e., hospitalization and death from COVID-19) and those that might be increased after vaccine inoculation (i.e., venous thromboembolism). The incidence rate ratios (IRR) of vaccinated and unvaccinated citizens are separately estimated within strata of sex, age category and vaccine type. When suitable, number needed to treat (NNT) and number needed to harm (NNH) are calculated to evaluate the balance between the benefits and harm of vaccines within each sex and age category. Results. In total, 2,351,883 citizens are included because they received at least one dose of vaccine (755,557 Oxford-AstraZeneca and 1,596,326 Pfizer/Moderna). A reduced incidence of COVID-19-related outcomes is observed with a lowered incidence rate ranging from 55% to 89% and NNT values ranging from 296 to 3977. Evidence of an augmented incidence of harm-related outcomes is observed only for women aged <50 years within 28 days after Oxford-AstraZeneca (being the corresponding adjusted IRR of 2.4, 95% CI 1.1-5.6, and NNH value of 23,207, 95% CI 10,274-89,707). Conclusions. A favourable balance between benefits and harms is observed in the current study, even among younger women who received Oxford-AstraZeneca.

COVID-19 vaccine hesitancy among undocumented migrants during the early phase of the vaccination campaign: a multicentric cross-sectional study.

STUDY OBJECTIVES: The marginalisation of undocumented migrants raises concerns about equitable access to COVID-19 vaccination. This study aims to describe migrants' hesitancy about the COVID-19 vaccination during the early phase of the vaccination campaign. SETTING: This multicentric cross-sectional survey was conducted in health facilities providing care to undocumented migrants in the USA, Switzerland, Italy and France in February-May 2021. PARTICIPANTS: Eligibility criteria included age >16 years, being of foreign origin and living without valid residency permit in the country of recruitment. A convenience sample of minimum 100 patients per study site was targeted. PRIMARY AND SECONDARY OUTCOME MEASURES: Data were collected using an anonymous structured questionnaire. The main outcomes were perceived access to the local COVID-19 vaccination programme and demand for vaccination. RESULTS: Altogether, 812 undocumented migrants participated (54.3% Geneva, 17.5% Baltimore, 15.5% Milano and 12.7% Paris). Most (60.9%) were women. The median age was 39 years (interquartile range 1). Participants originated from the Americas (55.9%), Africa (12.7%), Western Pacific (11.2%) Eastern Mediterranean (7.9%), Europe (7.6%) and South-East Asia (4.7%). Overall, 14.1% and 26.2% of participants, respectively, reported prior COVID-19 infection and fear of developing severe COVID-19 infection. Risk factors for severe infection were frequently reported (29.5%). Self-perceived accessibility of COVID-19 vaccination was high (86.4%), yet demand was low (41.1%) correlating with age, comorbidity and views on vaccination which were better for vaccination in general (77.3%) than vaccination against COVID-19 (56.5%). Participants mainly searched for information about vaccination in the traditional and social media. CONCLUSIONS: We found a mismatch between perceived accessibility and demand for the COVID-19 vaccination. Public health interventions using different communication modes should build on trust about vaccination in general to tackle undocumented migrants' hesitancy for COVID-19 vaccination with a specific attention to men, younger migrants and those at low clinical risk of severe infection.

Protective action of natural and induced immunization against the occurrence of delta or alpha variants of SARS-CoV-2 infection: a test-negative case-control study.

BACKGROUND: The evolution of SARS-CoV-2 has led to the emergence of several new variants, and few data are available on the impact of vaccination on SARS-CoV-2 variants. We aimed to assess the association between natural (previous infection) and induced (partial or complete vaccination) exposure to SARS-CoV-2 and the onset of new infection supported by the delta variant, and of comparing it with that supported by alpha. METHODS: We performed a test-negative case-control study, by linking population-based registries of confirmed diagnoses of infection with SARS-CoV-2, vaccinations against Covid-19 and healthcare utilization databases of the Italian Lombardy Region. Four hundred ninety-six persons who between 27 December 2020 and 16 July 2021 had an infection by the delta variant were 1:1 matched with citizens affected by alphavariant and 1:10 matched with persons who had a negative molecular test, according to gender, age and date of molecular ascertainment. We used a conditional logistic regression for estimating relative risk reduction of either variants associated with natural and/or induced immunization and corresponding 95% confidence interval (CI). RESULTS: Previous infection was associated with 91% (95% CI 85% to 95%) reduced relative risk of reinfection, without evidence of significant differences between delta and alpha cases (p=0.547). Significant lower vaccinal protection against delta than alpha variant infection was observed with reduced relative risk associated with partial vaccination respectively of 29% (7% to 45%), and 62% (48% to 71%) (p=0.001), and with complete vaccination respectively of 75% (66% to 82%) and 90% (85% to 94%) (p=0.003). CONCLUSIONS: Lower protection towards infections caused by the delta variant with respect to alpha variant was noticed, even after the completion of the vaccination cycle. This finding would support efforts to maximize both vaccine uptake with two doses and fulfilment with individual protection measures, especially as the delta variant is rampant worldwide presently.

Change in healthcare during Covid-19 pandemic was assessed through observational designs.

OBJECTIVE: Methodological challenges for investigating the changes in healthcare utilization during COVID-19 pandemic must be considered for obtaining unbiased estimates. STUDY DESIGN AND SETTING: A population-based study in the Lombardy region (Italy) measured the association between the level of epidemic restrictions (increasing exposure during pre-epidemic, post-lockdown, and lockdown periods) and the recommended healthcare (outcome) for patients with schizophrenia, heart failure, chronic obstructive pulmonary disease, breast cancer, and pregnancy women. Two designs are applied: the self-controlled case series (SCCS) and the usual cohort design. Adjustments for between-patients unmeasured confounders and seasonality of medical services delivering were performed. RESULTS: Compared with pre-epidemic, reductions in delivering recommended healthcare during lockdown up to 73% (95% confidence interval: 63%-80%) for timeliness of breast cancer surgery, and up to 20% (16%-23%) for appropriated gynecologic visit during pregnancy were obtained from SCCS and cohort design, respectively. Healthcare provision came back to pre-epidemic levels during the post-lockdown, with the exception of schizophrenic patients for whom the SCCS showed a reduction in continuity of care of 11% (11%-12%). CONCLUSION: Strategies for investigating the changes in healthcare utilization during pandemic must be implemented. Recommendations for taking into account sources of systematic uncertainty are discussed and illustrated by using motivating examples.

Effects of the early phase of the COVID-19 pandemic on natural and ART-mediated birth rates in Lombardy Region, Northern Italy.

RESEARCH QUESTION: What effects did the early phase of the COVID-19 pandemic have on natural and assisted reproductive technology (ART)-mediated birth rates? DESIGN: Regional registries were consulted with permission from the Health Authorities of Lombardy Region, Northern Italy, an area particularly affected by the early phase of the epidemic. Deliveries occurring in the area between 1 January 2019 and 31 December 2020 from women beneficiaries of the National Health System and resident in Lombardy were identified. Comparisons mainly focused on December 2020, when women who conceived after 8 March (the start of the stringent lockdown imposed by the authorities) were expected to deliver. RESULTS: When comparing the periods January to November in 2019 and 2020, a 5.1% reduction of monthly general birth rate (from 5732 in 2019 to 5438 in 2020) was observed. The contribution of ART births was similar in 2019 and 2020, being 4.4% and 4.5%, respectively. In December 2020, a notable drop in natural (-17.8%), ART-mediated (-86.6%) and overall (-21.0%) births was observed compared with December 2019. After adjusting for the expected 5.1% reduction, the inferred effect of the COVID-19 crisis corresponded to a 16.7% reduction in birth rate, of which 76% was related to natural (707 births) and 24% to ART (218 births) conceptions. CONCLUSIONS: This is the first study providing population-based evidence on the effects of COVID-19 and its related stringent restrictions on birth rates. The birth rate was dramatically reduced following the critical period, and the closure of ART centres played only a marginal role (24%) in the overall detrimental effect.

Effects of SARS-CoV-2 pandemic on follow-up and pharmacological treatment of chronic diseases in undocumented migrants.

BACKGROUND: All over the world, the COVID-19 pandemic, not unlikely other epidemics, has hit harder people in low socioeconomic conditions.In Western countries, undocumented migrants are a growing component of this disadvantaged segment of the population.Their health conditions are frequently burdened by a number of chronic conditions, and they experience many difficulties in accessing public health services. Frequently, the only medical assistance they can get is provided by non-governmental organisations. METHODS: We studied the medical records (including pharmacological treatments) of all patients attending the outpatient clinics of Opera San Francesco (OSF; a big charity in Milano, Italy), in the first 5 months of 2020. These comprise the outbreak of the pandemic and the lockdown period. The 1914 patients (1814 undocumented migrants and 100 Italians) seen during the lockdown were compared with those seen in the same period of 2019 and with those seen in the preceding months of 2020. We especially focused on three chronic conditions: cardiovascular diseases, diabetes and psychiatric disorders. RESULTS: The number of consultations during the first 5 months of 2020 was much smaller than that of the same period of 2019. During the lockdown, we found 4048 consultations for 1914 patients, while they were 8051 in the same period of 2019 and 5681 in the first 2 months of 2020.The quantity of medicines dispensed by OSF showed a marked decrease in the period of the study and mainly during the lockdown.The decrease in consultations and dispensation of medicines was most evident for psychiatric patients and almost not existent for patients with diabetes. Female patients suffered a more pronounced reduction. CONCLUSIONS: Western countries need strategies to better assist the very poor during epidemics.Differences among different groups of disadvantaged persons should be taken into account when designing recovery plans.

Undocumented migrants during the COVID-19 pandemic: socio-economic determinants, clinical features and pharmacological treatment.

Population groups such as undocumented migrants have been almost completely forgotten during the COVID-19 pandemic, though they have been living in all European countries for decades and new arrivals have continued throughout the pandemic. The aim of this study was to investigate their health conditions during the current pandemic. We analysed the records of 272 patients with respiratory issues attending the outpatient clinic of a large charity in Milan, Italy: amongst them, 18 had COVID-19 confirmed by rhino-pharyngeal swab and 1 of them deceased. All the patients attending the clinic appeared to have several risk factors for COVID-19 and chronic conditions suspected to predispose to the disease and/or to worsen severity and outcomes: hypertension, immunosuppression and previous close contact with COVID-19 patients were the most important ones. Presenting symptoms were worse in patients with COVID-19 than in those with other respiratory issues. These results are discussed in light of the necessity to provide better healthcare to undocumented migrants.