Vaccination is also optional. No one has said it is a duty..... “I’ve been sleepy since I was vaccinated. I can’t get rid of my chronic drowsiness.” I don’t know What are the factors that cause measurement errors? measuring Errors measurement environmental impaired I don’t know if his symptoms are acute or chronic because I’m not his doctor. However, it is unusual for him to be sleepy, as he is always actively looking for someone’s weaknesses. In any case, I feel that the number of people who catch a common cold has decreased recently. Almost no one around me is coughing. I always saw people catching colds from autumn to winter, but for that very reason the patients were exempt from working. The number of people who cough has decreased recently, but instead, almost everyone wears a mask on their face. We wear masks in summer and spring, and of course in autumn and winter. Of course there are exceptions. What are the factors that cause m...