[单选题]Text 4 As the nation experiences one of the worst flu seasons in years,thousands of Americans have already died from influenza,according to the U.S.Centers for Disease Control and Prevention.Though the season peaked in February,the CDC recently warned that we should prepare for a second wave of cases to hit before we emerge from the season entirely.Now,it appears more than 50,000 could die from the flu before the season ends.Perhaps most troubling is that this year marks a century since the deadliest viral outbreak in human history,which claimed the lives of 670,000 American men,women and children and as many as 50 to 100 million people worldwide.Among the lessons medical researchers gleaned from the catastrophic event is the critical importance of getting vaccinated.It's a lesson that much of the public continues to ignore,even as our scientific understanding of communicable diseases continues to grow.-The strain in tlus flu season,H3N2,is particularly nasty.It's similar to the HINl strain that set off the 1918 influenza pandemic,and it has resulted in high rates of death,particularly among the elderly.Researchers have struggled to create effective vaccines for the H3N2 strain;this year's flu vaccine is only about 36 percent effective at protecting against the virus,compared to an average of 45 percent over the past seven years.Nonetheless,it does provide some protection,and the unvaccinated are hit much harder without it.Earlier this year,a healthy young man from Pittsburgh did not get vaccinated and died soon afier getting the flu.While low vaccine efficacy means that those who get vaccinated can still contract the flu,it remains common sense and good civic behavior to get vaccinated.As a result of herd immunity,even low efficacy vaccines are enough to curb a pandemic from happening if vaccination rates are high.Flu vaccines did not exist during the pandemic of 1918,which is why it was so deadly.Yet year after year few Americans bother to get vaccinated.In economic terms,the herd immunity benefits of vaccination are a"public good."If I am vaccinated,I cannot exclude anyone from the herd immunity that I now offer.Similarly,someone enjoying my herd immunity does not diminish someone else's ability to enjoy my herd immunity.What typically happens when a public good like the flu vaccine is available is that many,perhaps most,people underinvest.They free ride off other people who get the vaccine.If too many people opt out of vaccination,communities become wlnerable to flu epidemics.According to the CDC,only 38 percent of the population chose to get vaccinated as ofNovember 2017.Low rates ofvaccination are particularly dangerous for children and the elderly,who are especially susceptible to influenza.As individuals,we have veU little control over the strain of the flu that emerges in a given year,or the efficacy of a vaccine,but we do have complete control over whether we get vaccinated.The public's response to a bad fiu outbreak or to low vaccine efficacy should be an increase in flu vaccinations,not a decrease.38.According to the text,there is no doubt about the infiuenza vaccines that
A.low efficacy vaccines can also help with vaccination accepted.
B.those who get vaccinated would not be infected.
C.the idea of herd immunity is a common sense.
D.many Americans are willing to get vaccinated.