2.1 Study design

This research used a repeated cross-sectional design. Data was collected during two waves of a routine monitoring survey of students' lifestyle and wellbeing at one of the largest universities in Saint-Petersburg (Russia). All research protocols and procedures were reviewed and approved by the Ethics Committee of Herzen State Pedagogical University of Russia (IRB00011060, record #19).

A convenience sample of university students was recruited into the routine monitoring online survey of students' life conducted by university officials. The section of items regarding the pandemic presented in the dataset was integrated in this monitoring study. Students were notified about the study via university based social media and communication platforms and encouraged to participate on the basis of anonymity. No compensation for the participation in the study was provided. All the data collection was implemented online. The participants provided consent before a data collection, indicating that they had read and understood the conditions of participation and the aims of the study. Among those who clicked on the invitation to participate in the study and read informed consent 97.2% agreed to participate.

There were two waves of data collection in this study. First wave took place in May–June 2020, second wave in September-November 2020. Since some of the students graduated and left university while others enrolled in the university between those two events, we excluded the graduate student's responses from the first wave dataset and first-year students from the second wave dataset. This enabled the study to include only those who were university students during both waves of data collection.

The dataset is presented in the two forms. The vertical format of dataset combined from the both waves consist of 1,790 observations (n = 1,017 in first wave and n = 773 in second wave) from a predominately female student population (86.4% of total sample, 86.7% in first wave, 85.9% in second wave). The average age of study participants was 20.77 years (SD = 2.78). In the first wave of data collection the average age of study participants was 20.79 years (SD = 3.00), in the second wave-−20.73 years (SD = 2.47).

Since the participation was anonymous to keep opportunity to merge data about same participants from different waves the participants were encouraged to create their personal code. Data from small subset of respondents (N = 197) which were identified as participated in the both waves was merged in the horizontal dataset which provides opportunity to analyze the-individual changes.

The spread of COVID-19 in each country has its own unique characteristics (e.g., Feng et al., 2020; World Health Organization, 2020a). Thus, in the early stages of the pandemic, there was no consensus regarding the future trajectory of COVID-19 (Scudellari, 2020; Brüssow, 2021). In Russia by the middle of April 2020, COVID-19 cases had been detected in all its federal regions. St. Petersburg is one of the largest cities in the country and which has one of the most intensive spread of COVID-19 epidemic (Akimkin et al., 2021). The first round of data collection occurred at the peak of the first wave of COVID-19 pandemic in Russia (03/30/2020 to 08/30/2020) with an incidence of 51.31 cases per 100,000 people (Akimkin et al., 2022). In the study site a set of restrictive measures combined with the introduction of “non-working days” (03/30/2020 to 05/11/2020) was implemented. As a result university campuses were closed, and all learning, teaching, and assessment was moved online (Watermeyer et al., 2021).

The second round of data collection was at the beginning of the second wave of COVID-19 (08/31/2020 to 05/09/2021) after a decline in infections during the summer months. The number of daily confirmed cases exceeded the peak of the first wave and the number of daily confirmed deaths also was rapidly increasing (Mathieu et al., 2020). At that moment in Russia universities worked in a blended format but no lockdown was introduced.

Although the first vaccine against COVID-19 was registered in Russia in August 2020, mass vaccination was not available in Russia until December 4, 2020. That is why non-medical means of protection such as individual health-protective behavior were the only possible means to mitigate the spread of COVID-19 during both rounds of data collection.