In addition to the small quantitative change of antigenic drift, there is also a qualitative change, that is, antigenic shift, in which the surface antigens HA and NA of influenza A viruses are completely mutated, and this shift often causes a worldwide pandemic of influenza.

The influenza vaccines we usually inject are against several common human influenza subtypes, such as seasonal H1 and H3, and Yamagata and Victoria types of influenza B.

Therefore, although the flu vaccine changes every year, it cannot keep up with the natural mutation of the flu virus.

Zhen Zhen's mother complained: "So, is it useless for us to get the flu vaccine usually?"

"Not really. "Although the influenza virus mutates rapidly, the antigens contained in the influenza vaccine have cross-immune protection against influenza viruses at different epidemic periods, and the influenza vaccine will reduce the symptoms after reinfection with the influenza virus." ”

"In this way, the flu vaccine still has some effect, at least, I was not infected by your father, Fang Shinan's symptoms are also worse than your father's, your father is now transferred to the general isolation ward, but Shi Nan is ......"

When Zhen Zhen's mother said this, she couldn't help but feel sad in her heart, Fang Shi Nan is a colleague of Zhen Zhen's father, and she is also familiar with Zhen Zhen's mother, a big living person, who was originally fine, died suddenly, which is very sad and panicked.

Zhen Zhen comforted her mother, "Mom, it may or may not be the cause of the flu vaccine, after the cross-racial transmission of the flu virus, it will always cause serious reactions in some individuals, but there is no proof that bird flu can spread between people, as long as you usually do a good job of protection and do not contact sick and dead birds, it will reduce the possibility of infection." ”

As Ye Zhenzhen was talking, the TV in the hospital corridor also began to broadcast information related to the bird flu epidemic in Y City.

On the TV program, the spokesperson of the health department of Y city was interviewed by the host, and the spokesman informed the public about the first human avian influenza outbreak in Y city this year.

It reported in detail the process and prevention and control measures taken by the suspected patients from the receipt of the report to the laboratory diagnosis, answered the questions of public concern, as well as the progress of the epidemic, the disinfection and control of the epidemic site, the medical observation and sampling and testing of close contacts, and the treatment of patients.

Zhen Zhen and Zhen Zhen's mother were watching the program on the TV in the corridor intently, when suddenly, a familiar voice sounded behind them, "The principle of immediacy and follow-up of information disclosure has been done very well in this bird flu outbreak in Y City. ”

Zhen Zhen looked back and saw that Nan Zhiqiao was standing behind him at some point, and his handsome and upright figure was as usual.

"Senior Nan, has the matter been handled by the CDC?"

Nan Zhiqiao has been busy with the Y City CDC for the past two days, and only in the evening does he have time to come to the hospital to see Zhen Zhen's father's situation, and now it is the morning, and H Hospital suddenly appeared, Zhen Zhen couldn't help but ask curiously.

"Well, it's almost done, and the rest of the matter will be handled by the local health department, I'll take a look at my uncle's situation. ”

"My dad is in stable condition, and the doctor said that he will be discharged home after the avian flu quarantine period. ”

Nan Zhiqiao looked at Zhen Zhen's mother's haggard face, and said with concern: "Auntie, you go home and rest for a while, the hospital is here with me and Zhen Zhen guarding, and in the evening, we will change shifts." ”

Since Zhen Zhen's father was hospitalized, several people have not rested well, Zhen Zhen and Zhen Zhen's mother have been guarding the hospital, and at the same time, as close contacts, they have carried out examinations and preventive treatment, Nan Zhiqiao is even harder, the hospital disease control runs at both ends, and he has to go to the disease control side to deal with the epidemic during the day, and he has to come to the hospital to see Zhen Zhen's father at night.

Zhen Zhen's mother resolutely disagreed with going home by herself, and pushed Zhen Zhen and Nan Zhiqiao to let the two go home to rest first.

Unable to resist Zhen Zhen's mother, Zhen Zhen decided to go home with Nan Zhiqiao first, and then change her mother to go back when the lunch break came.

——

On the way home for the two, Nan Zhiqiao's brows kept frowning slightly, as if she had something on her mind, and Zhen Zhen asked with concern: "Senior Nan, are you still worried about this bird flu epidemic?"

"Nope. Nan Zhiqiao denied it, worried that Zhen Zhen would not believe it, and then explained: "The avian flu epidemic in Y City, the emergency response work has been done very well, as long as there are no new cases of human avian influenza, the epidemic will gradually disappear with the original cases being cured and discharged from the hospital and a large number of poultry and waterbirds being killed and harmless." ”

"There are only two cases of avian influenza in Y city, and they are clusters, which are more contagious than purely sporadic cases, and there was a cluster outbreak of avian influenza in a large family in Indonesia with a high mortality rate. ”

Nan Zhiqiao: "You're talking about a village in northern Sumatra, Indonesia, where there was a cluster of eight cases of human infection with avian influenza H5N1 in a large family, seven of which were laboratory-confirmed, six died, and none of the close contacts or family members became ill.

The first patient in the family, a 37-year-old female, became ill on 27 April 2006, began to cough frequently two days later, and died of severe respiratory illness on 4 May.

On 29 April, the first female patient died on 9 May and 12 May, the first of the two sons of the female patient's extended family, the first two cases to be confirmed in the cluster.

On May 10, the sister of the first patient died, and on May 14, the 18-month-old daughter of the sister of the first patient died.

On May 13, the nephew of the first patient died, and on May 22, the younger brother of the first patient died.

All of the above, who attended the family gathering on April 29, had three cases, namely the first patient's two sons and 25-year-old brother, who were in a small room with the first patient who already had cough symptoms that night, and the other confirmed cases lived near the home of the first patient.

All confirmed cases had prolonged close contact with a critically ill case of avian influenza. ”

Nan Zhiqiao completely told the details of a cluster case of avian flu that happened abroad a few years ago, Ye Zhenzhen was surprised, "Senior Nan, you remember the case so clearly?!"

"When I did the sequence analysis a few days ago, I happened to use the sequence of the strain isolated from the cluster case in Indonesia, so I was more impressed. ”

"Senior Nan, the scale of the family cluster in Indonesia is the largest among all the reported H5N1 cluster cases, and the analysis of the influenza virus sequence isolated from the cases should be found, right?"

"Yes, the eight gene fragments of the H5N1 virus strain isolated from this family cluster are identical, and the sequences are very similar to those of the virus strains isolated from poultry in the region.

The influenza virus isolated from the younger brother and father of the first patient had the same genetic mutations, with 21 mutations, involving 7 of the 8 genes of the virus!"