The objective of this study will be to evaluate the effect of vaccination on breath volatile organic compounds (VOC) content.

By capturing and analyzing the breath of anti-COVID-19 50 vaccinated subjects during the period of antibody production, the investigators will determine and quantify all the compounds associated with the body reaction to the COVID-19 antigen.

The major VOCs in the breath of healthy individuals are isoprene (12-580 ppb), acetone (1.2-1,880 ppb), ethanol (13-1,000 ppb), methanol (160-2,000 ppb), and other alcohols.

Rapidly growing serological evidence shows that IgM, IgG, and IgA antibodies against the S or N proteins evolve rapidly in the serum of asymptomatic as well as symptomatic COVID-19 patients within a week of infection or symptom onset and stay elevated with progressing disease.

Since the standard serology testing at Shamir Medical center tracks the presence of IgG only, those serologic tests will be conducted before and 48 hours following the second vaccination dose.

Nevertheless, since IgM antibodies are known to be produced by four to seven days following the first dose of vaccination, although IgM serology testing cannot be performed, the investigators are interested in sampling breath at this time range, in order for them to correlate it with the changes in the subjects' physiologic condition.

Since this is an unknown metabolic volatile compound mixture, the goal will be to identify compounds and quantify them with a high level of precision and subsequently correlate them with the disease.