Evaluation of the Effectiveness of the Policy of Holding the Second Dose of Vaccination: Lessons from the Outbreak in Ho Chi Minh City

Abstract

The coronavirus disease 2019 (COVID-19) pandemic has caused a lot of ethical controversy in the equal provision of healthcare, including vaccination. Therefore, our study was designed to assess the impact of Ho Chi Minh City's policy to hold the second dose of the COVID-19 vaccine. Using a cross-sectional study design to assess low saturation of peripheral oxygen (SPO2) risk based on vaccination status, we included patients who were confirmed to have SARS-CoV-2 and were treated at home. The stepwise method was used to determine participants' low SPO2 risk-related factors. The average age of the 2836 respondents was 46.43 ± 17.33 (years). Research results have shown that seven factors are related to the low SPO2 status of participants, including age, sneezing, shortness of breath, coughing, and fainting as COVID-19 symptoms, the number of people living with COVID-19, and a history of lung disease. A statistically significant (p = 0.032) finding in this study was that fully vaccinated patients had a 6% lower risk of low SPO2 compared to the first dose less than 21 days group. This result was similar in the vaccine holder group (p < 0.001). Holding the second dose of the COVID-19 vaccine is associated with a lower SPO2 risk than that of fully vaccinated patients. Therefore, this approach should be considered by governments as it could bring a greater benefit to the community.

Keywords: COVID-19; Vietnam; health policy; holding the second vaccine dose; low- and middle-income countries; vaccination.

Figure 1

The relationship between the duration of COVID-19, the number of clinical symptoms, and vaccination type. Three colors have been used to represent the characteristics of COVID-19 patients, as follows: red represents patients with “first dose < 21 days”, green for “holding the second doses”, and blue for “fully vaccinated”. (A,C) use density histograms to show the distribution of the study subjects from the time of illness to the time of the survey, and the number of symptoms of COVID-19 patients. (B) uses a scatterplot to show the relationship between the duration of illness and the number of symptoms, and the size of the circle corresponds to the time between the last vaccination and the survey. Loess regression was used to draw smoothing lines according to the vaccination status of COVID-19 patients. Time of vaccination refers to the time from the last dose of the vaccine to the time of study participation.

Figure 2

The relationship between the time from vaccination to confirmed COVID-19 and the SPO₂ index by the time of confirmation and vaccination status. Three colors have been used to represent the characteristics of COVID-19 patients, as follows: red represents patients with “first dose < 21 days”, green for “holding the second doses”, and blue for “fully vaccinated”. (A,C) use density histograms to show the distribution of the study subjects from the time of illness to the time of the survey and the SPO₂ index. (B) uses a scatterplot to show the relationship between the duration of illness and the SPO₂ index, and the size of the circle corresponds to the time between the last vaccination and the survey. Loess regression was used to draw smoothing lines according to the SPO₂ index of patients. The time of vaccination refers to the time from the last dose of the vaccine to the time of study participation.