Analyses to evaluate the efficacy of COVID-19 vaccinations are limited, and there is a lack of evidence on the indirect protection of children through the immunization of household members. Prior to receiving a real-time reverse transcriptase-polymerase chain reaction (RT-PCR) test for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) between September 1, 2021 and December 5, 2021, researchers collected information on 12,442 patients younger than 18 about the vaccination status of their household members, their vaccine preferences and doses, and their previous history of COVID-19 infection. About 18% (2,289) were immunized; this included 91.4% who were given the BNT162b2mRNA vaccination and 8.6% who were given the inactivated COVID-19 vaccine. Compared to younger children, older children had a considerably greater rate of positive in real-time RT-PCR [odds ratio (OR), 1.34; 95% confidence interval (CI), 1.21-1.47] and in real-time RT-PCR [P<0.001]. There was a statistically significant reduction in SARS-CoV-2 infection in the vaccinated group (both those who received the full complement of vaccine and those who received only a portion) (P<0.001). The odds of contracting COVID-19 were higher among children who were either not vaccinated (OR, 4.88; 95% CI, 3.77-6.13) or just partially vaccinated (OR, 1.83; 95% CI, 1.52-2.12) than among those who had received all recommended doses of vaccination. Patients’ COVID-19 real-time RT-PCR positive rates were not correlated with their household members’ vaccination histories or vaccination preferences (P>0.05 for both). Children who were immunized, particularly with mRNA vaccines, had much decreased incidence of SARS-CoV-2 infection. Children who have not been vaccinated against COVID-19 may only be partially protected by the immunization of other members of their households. It is still essential for children to get their own vaccinations.