key: cord-0858694-e6dheaeb
authors: Iftime, S.; Lopez-Azcona, A. F.; Vallverdu, I.; Hernandez-Flix, S.; de Febrer, G.; Parra, S.; Hernandez-Aguilera, A.; Riu, F.; Joven, J.; Camps, J.; Castro, A.; Group, REUSCOVID Study
title: First and second waves of coronavirus disease-19: A comparative study in hospitalized patients in Reus, Spain
date: 2020-12-11
journal: nan
DOI: 10.1101/2020.12.10.20246959
sha: 9e2bd7bcc069430642e167dd1f35c34af309c67b
doc_id: 858694
cord_uid: e6dheaeb

Many countries have seen a two-wave pattern in reported cases of coronavirus disease-19 during the 2020 pandemic, with a first wave during spring followed by the current second wave in late summer and autumn. Empirical data show that the characteristics of the effects of the virus do vary between the two periods. Differences in age range and severity of the disease have been reported, although the comparative characteristics of the two waves still remain largely unknown. Those characteristics are compared in this study using data from two equal periods of 3 and a half months. The first period, between 15th March and 30th June, corresponding to the entire first wave, and the second, between 1st July and 15th October, corresponding to part of the second wave, still present at the time of writing this article. Two hundred and four patients were hospitalized during the first period, and 264 during the second period. Patients in the second wave were younger and the duration of hospitalization and case fatality rate were lower than those in the first wave. In the second wave, there were more children, and pregnant and post-partum women. The most frequent signs and symptoms in both waves were fever, dyspnea, pneumonia, and cough, and the most relevant comorbidities were cardiovascular diseases, type 2 diabetes mellitus, and chronic neurological diseases. Patients from the second wave more frequently presented renal and gastrointestinal symptoms, were more often treated with non-invasive mechanical ventilation and corticoids, and less often with invasive mechanical ventilation, conventional oxygen therapy and anticoagulants. Several differences in mortality risk factors were also observed. These results might help to understand the characteristics of the second wave and the behaviour and danger of SARS-CoV-2 in the Mediterranean area and in Western Europe. Further studies are needed to confirm our findings.

Accepting an alpha risk of 0.05 and a beta risk of less than 0.2 in a bilateral contrast, it takes 108 137 subjects in the first wave and 105 in the second wave to detect a difference equal to or greater 109 than 8 years in the variable age. The common standard deviation is assumed to be 22. A follow-up 110 loss rate of 0% was estimated. 111

Data is given as numbers and percentages or means and standard deviations. Statistical 113 comparisons between two groups were made using the χ 2 test (categorical variables) or the 114 Student's t test. Logistic regression models were fitted to investigate the combined effect of selected 115 variables on mortality. Statistical significance was set at p ≤0.05. All calculations were made using 116 the SPSS 25.0 statistical package (SPSS Inc., Chicago, IL, USA). 117

The raw data of this study are as Supporting Information. During the study period, 468 119 patients with SARS-Co-V2 infection, confirmed by RT-PCR, were admitted to the hospital. The 120 seasonal distribution of hospital admissions is shown in Figure 1 . The first wave peaked at the end 121 of March and was followed by a progressive decrease with very few patients being admitted in May 122 and June. The number of cases fluctuated upward from mid-July until a sharp increase in mid-123

October. The number of patients admitted was 204 in the first wave and 264 in the second one. 124

Those in the second wave were significantly younger (58 ± 26 vs. 67 ± 18 years; p <0.001). A 125 noteworthy feature of the second wave was the high number of children between 0 and 9 years of 126 age (n = 21), 12 of them being babies under 1 year (Figure 2 ). The department to which the patients 127 were admitted is shown in is the author/funder, who has granted medRxiv a license to display the preprint in (which was not certified by peer review) preprint

The copyright holder for this this version posted December 11, 2020. ; https://doi.org/10.1101/2020.12.10.20246959 doi: medRxiv preprint second wave, so the case fatality rate decreased from 24.0% to 13.2%. The patients who died were 132 significantly older than the survivors and those who died in the second wave were older than those 133 in the first wave (83 ± 10 vs. 78 ± 13 years; p = 0.042). 

Results are shown as number of cases and percentages (in parenthesis) or as means ± standard deviations. is the author/funder, who has granted medRxiv a license to display the preprint in (which was not certified by peer review) preprint

The copyright holder for this this version posted December 11, 2020. ; https://doi.org/10.1101/2020.12.10.20246959 doi: medRxiv preprint Finally, we wanted to identify which factors were the most important determinants of death 177 in the two groups of patients. Logistic regression analyses highlighted the importance of age, fever, 178 dyspnea, acute respiratory distress syndrome, type 2 diabetes mellitus, and cancer in the first wave is the author/funder, who has granted medRxiv a license to display the preprint in (which was not certified by peer review) preprint

The copyright holder for this this version posted December 11, 2020. is the author/funder, who has granted medRxiv a license to display the preprint in (which was not certified by peer review) preprint is the author/funder, who has granted medRxiv a license to display the preprint in (which was not certified by peer review) preprint

The copyright holder for this this version posted December 11, 2020. ; https://doi.org/10.1101/2020.12.10.20246959 doi: medRxiv preprint on average 5 years older than the victims of the first wave. Moreover, fewer patients required 211 respiratory assistance via invasive mechanical ventilation methods. This improvement in the results 212 of admitted patients might be linked to the fact that the health system in our country, as in many 213 others, has since become better prepared. We have more experience and better treatment regimens, 214 and we carry out more diagnostic tests, allowing serious cases to be detected early and to receive frequently with dexamethasone, as suggested by the RECOVERY study [14] , and 217 hydroxychloroquine and loponavir-ritonavir were substituted by remdesivir and tocilizumab, which 218 several studies have reported to be more effective than in preventing death and shortening the 219 duration of hospital stays [15] [16] [17] . Another factor that might have contributed to the decrease in the 220 case fatality rate is the improvement in environmental conditions. For example, warm weather and 221 improved air quality following the city lockdown have been reported to correlate negatively with 222 SARS-CoV-2 transmissibility [18] [19] [20] . 223 A new and remarkable characteristic of the incidence of COVID-19 in this second wave in 224 our population is the higher incidence in babies, children and pregnant women who went to the 225 hospital to give birth or in post-partum women. The vast majority of these patients did not present 226 serious symptoms and so did not require hospitalization for more than 4 days. There were no deaths 227 among children up to 9 years of age, pregnant or post-partum women. The predominant symptom 228 presented by the children was fever (19 out of 21 cases, 90.5%), while pregnant and post-partum 229 women (13 and 17 cases, respectively) were asymptomatic and promptly discharged. These results 230 highlight the role of family contact in the transmission of the virus and agree with previous reports 231 that have indicated the generally low severity of the disease in these patients [21] [22] [23] [24] . 232

The predominant symptoms of infection (fever, dyspnea, pneumonia cough) were similar in 233 both waves, although the patients in the second wave presented renal (acute kidney failure) and 234 gastrointestinal symptoms (vomiting, abdominal pain) more frequently. Indeed, the Spanish 235

Ministry of Health has already highlighted, in a document updated on 2 nd October, the higher 236 . CC-BY-NC-ND 4.0 International license It is made available under a perpetuity.

is the author/funder, who has granted medRxiv a license to display the preprint in (which was not certified by peer review) preprint

The copyright holder for this this version posted December 11, 2020. ; https://doi.org/10.1101/2020.12.10.20246959 doi: medRxiv preprint

Characteristics second wave: a study in 53 countries or regions

Epub ahead of print

First and second

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