The latent term
Case 216
【Progress】
Her symptom of mild fever appeared four days after infection. She received treatment of steroid and antiviral agents. Eight days after, PO2 decreased to 90 mmHg in room air and increase during O2 inhalation of 2mL/min. At the time of 15 days after infection, she is still admitted in our hospital.
【Discussion】
In Japan, the number of patients with influenza was approximately 1.5 million in 2018 and of these, 3325 people were dead (death rate 0.022%). Meanwhile, the number of patients with COVID19 was 87639 during January 1st to October 10th and of these, 1616 people were dead (death rate 1.8%). It indicates that although the number of dead patients with COVID19 is relatively small compared to those with influenza, the death rate was much higher, almost 100 times higher in a COVID19 group than in an influenza group. This is probably due to that COVID19 is a new virus indicating diagnosis is apt to be delayed and no antibody for treatment is supplied.
In USA, the number of patients with influenza was approximately 35 million in 2018 and of these, 34000 people were dead (death rate 0.1%). Meanwhile, the number of patients with COVID19 was 7894478 during January 1st to October 10th and of these, 218648 people were dead (death rate 3%). The number of dead patients with COVID19 is much greater than those with influenza in USA.
Namely, in influenza comparison of Japan vs USA, the death rate was 0.02 vs 0.1 while in COVID19 comparison, the death rate was 1.8% vs 3%. The number of dead patients in Japan was a half of COVID19 compared to influenza. The number of dead patients with COVID19 in USA is six times greater than those with influenza.
The current population at October 11th of Japan vs USA, is 126383545 vs 331549373: 2.6 times greater in USA than in Japan. The number of patients with influenza was 1.5 million vs 35 million: 23 times greater in USA. The number of patients with COVID19 was 87639 vs 7894478: 93 times greater in USA. It indicates the patients with influenza is 23/2.6 (8.8) times greater per population in USA vs Japan and the patients with COVID19 is 93/2.6 (36) times greater per population.
The death number of Japan vs USA was 3325 vs 34000 by influenza (1 : 10.2) and it was 1616 vs 218648 by COVID19 (1 : 135). This ratio is estimated by national population as 3.9 (10.2/2.6) by influenza and 51.9 (135/2.6).
What brought this difference is not clarified: race, health care habit, medical support. The incidences of falling into influenza or COVID19 and the death rate by these diseases are reported to be greater in poor blacks than wealthy whites. BCG vaccine might be one of the persuasive reasons. BCG vaccination is mandatory in Japan but not in USA. It is known to strengthen the primary immunity of macrophages.
Influenza outbreak usually occurs in winter but rarely in summer. Where do influenza viruses live in or move ? One of the hypotheses is that they survive in swine where human influenza viruses and avian influenza viruses enter swine, and both viruses mix leading to the newly altered influenza viruses arise. Another hypothesis comes up with that influenza viruses outbreaking in the northern hemisphere move to the southern hemisphere through human travelling. The current situation is the human migration is limited, and then, influenza outbreak does not happen this winter. The influenza outbreak is reported to happen least this season in Australia and New Zealand.
It is reported that the latent periods from infection to onset is 2 to 7 days and the turning point whether worsening or not is another 5 to seven days from the onset. In our case, the latent period is four days and the turning point from slight degree to moderate degree is the next 4 days. The signs and symptoms were getting worse at time of the fifteen days from the infection. She has a risk of advanced age of 80, indicating the weakness of immunity.
【Summary】
We presented an eighty-year-old female with COVID19. It took four days from the infection to the onset of slight fever, 37.5℃. Further it took four days from the onset to the worsening of the symptom and the expanding of the lesion on the follow-up chest CT. It is borne in mind that the latent periods from infection to onset is 2 to 7 days and the turning point whether worsening or not is another 5 to seven days from the onset.
In influenza comparison of Japan vs USA, the death rate was 0.02 vs 0.1 while in COVID19 comparison, the death rate was 1.8% vs 3%. The number of dead patients in Japan was a half of COVID19 compared to influenza. The number of dead patients with COVID19 in USA is six times greater than those with influenza. The number of patients with influenza was 1.5 million vs 35 million: 23 times greater in USA. The number of patients with COVID19 was 87639 vs 7894478: 93 times greater in USA. It indicates the patients with influenza is 23/2.6 (8.8) times greater per population in USA vs Japan and the patients with COVID19 is 93/2.6 (36) times greater per population. The death number of Japan vs USA was 3325 vs 34000 by influenza (1 : 10.2) and it was 1616 vs 218648 by COVID19 (1 : 135). The death ratio is estimated by national population as 3.9 (10.2/2.6) by influenza and 51.9 (135/2.6).
【References】
1.Last updated: October 09, 2020, 21:51 GMT. Coronavirus Worldwide Graphs
2.Japan health and labor ministry. homepage
2020.12.23