New Horizon in Mass Inoculation RICHARD L. TOWLE, M.A. immunization programs are beset in its course from the reservoir bottle to the MASSwith many difficulties, not least of which aperture, remains in a closed, sterile system. is the time-consuming operation associated Pressure for injection is applied to a plunger directly with inoculation of the vaccinee. by release of powerful springs. Power for Several years ago, U.S. Army scientists ap¬ cocking the springs is obtained from a hydrau¬ plied the jet injection principle (1) in the de¬ lic system activated by an electric motor. The velopment of an automatic multiple-dose entire process of loading the discharge chamber syringe (2) for immunizing large groups of with vaccine, cocking the drive springs, and people. This instrument, with some improve¬ inoculating the immunogen into the patient ments, has been employed on a limited scale requires only a few seconds. by the Armed Forces with encouraging results. East Pakistan is one of the few remaining The time required to vaccinate groups of men endemic areas of cholera in the world; the was much less when the jet injector was used Province usually suffers over 15,000 attacks and than when the ordinary syringe and needle 10,000 deaths yearly (6). It is probable that, method was followed. Moreover, experience owing to inadequate reporting of infectious dis¬ indicated that the immunological responses eases, these figures are not entirely reliable. elicited by several types of vaccine adminis¬ But it is known that cholera reaches two tered by jet injection were comparable to those peaks during the year, the first in May prior to obtained by the usual methods (3-5). the onset of the summer monsoon rains and the It remained to be determined whether the second starting in September at the end of the procedure which seemed practical for large- monsoon and continuing through the months scale immunization of military personnel of October, November, and December. might be equally useful for civilian groups. Immunizations in East Pakistan, except dur¬ The present report describes the results ob¬ ing emergencies such as the 1958 smallpox epi¬ tained in mass immunization programs in Paki¬ demic, are carried on by the limited staff of the stan in which cholera and typhoid vaccines Directorate of Health Services. The popula¬ Pakistan is 46 mil¬ were administered to the civilian population tion of East approximately lion There are about 400 by means of a Hypospray Multidose Jet In¬ people. sanitary jector (A). This instrument is compact, fit¬ inspectors, or about 1 per 100,000, each super¬ 2 to 3 health assistants who are ting into a container the size of an overnight vising responsi¬ suitcase. Vaccine is forced through a minute ble, among other duties, for the complete This means aperture under sufficiently high pressure so immunization of the people. only that the Jetstream penetrates the skin and 1 vaccinator and inoculator for approximately enters the subcutaneous tissue. The vaccine, every 40,000 persons. Immunization teams are handicapped by Mr. Towle is field sanitarian adviser with the Inter¬ travel conditions. There are comparatively national Cooperation Administrations U.S. Opera¬ few roads, rail service is limited, and air service tions Mission to Pakistan, Dacca, East Pakistan. within each Province is almost nonexistent. Vol. 75, No. 6, June 1960 471 These limitations, coupled with the fact that action would be as favorable among the less most of the land is under water for several educated groups, to which most of the popula¬ months during the monsoon, severely hamper tion of East Pakistan belong. These were the the mobility of the health workers. Within people exposed to disease, the ones who would each thana, a political unit of roughly 100,000 determine the effect of immunization efforts. population, nearly all local movement is con¬ During the following months, accompanied fined to foot or small country boats. by a Pakistani team usually comprising a doc¬ The psychological aspect of the use of the tor and two sanitary inspectors, I took the in¬ syringe and needle, itself is another obstacle to jector into many areas of the Province, immunization. In any population of any coun¬ inoculating for cholera. We inoculated people try, many people actually shrink from not only in areas easily accessible, in some almost com¬ the sight but the idea of the needle. This is pletely inaccessible, and in cities, small towns, true in East Pakistan so especially where many and market areas. We tried to select places are uneducated In comparatively villagers. which would give us a cross section of East many areas they do not understand the nature Pakistan. of disease or preventive measures. Not under¬ standing, they feel no stimulus to overcome the apprehension against the needle the way people Inoculations in Urban Areas might in other societies. The purdah system In mass inoculation in city areas, it is thought among the Moslem peoples further complicates that the machine proved itself without doubt. matters it difficult to reach by making extremely In most instances, inoculations were done from the female element of the population. a station wagon equipped with a generator Even the educated classes have misgivings which for the and about immunization because the of in¬ provided electricity injectors majority a and for There have been with an unsterilized microphone speaker publicity. jections given was no in a constant and with the risk of problem attracting crowds; syringe needle, transmitting line waited for inoculation. or which are com¬ malaria, syphilis, hepatitis, An excellent of the of the mon in this part of the world. example capability Taking these conditions into consideration, machines was shown in Dacca during the Oc¬ tober-November mass inoculation the task remained to prove the utility of the program machine in different areas and in various situations. Initially, demonstrations of the machine were given to different groups. This was done to familiarize community leaders with the jet in¬ jector and to determine the reaction of the peo¬ ple toward this new method of inoculation. Demonstrations were given to doctors, medical students, civic groups, health workers, the mili¬ tary, students, and various women's groups in Dacca and throughout the Province. In all instances the reaction was highly favorable. The fact that no needle was used seemed to im¬ press the people more than any other factor. Also encouraging were the numerous comments regarding the relative absence of pain and the speed of inoculation. Although the general response to these numer¬ ous demonstrations was completely positive, the majority of these people were of the educated classes. It remained to be seen whether the re- Hypospray Multidose Jet Injector 472 Public Health Reports against cholera. Thousands were inoculated were inoculated. The entire staff of the 30 cen¬ daily, with two injectors in operation. The ters, inoculating by syringe and needle, were highest figure for 1 day totaled 6,759. Sanitary only able to inoculate about the same number inspectors and doctors, working with syringe during the same period. and needle during the campaign, were report¬ As the work in a municipal area is carried on ing about 100 inoculations per inoculator per most successfully as an outdoor operation, most day. It was clearly indicated that one injector of the persons inoculated were men and chil¬ could do the work of 25 to 80 men. dren. Few women were reached in this situa¬ The only experience of inoculating with the tion because of the purdah system and the social injectors outside of East Pakistan was in the restrictions on women moving about in public. first week of July in Karachi, West Pakistan. To overcome this difficulty, we set up special Owing to excessive rainfall in June, much of centers in buildings for women only. Attend¬ Karachi was flooded. Nearly all of the refugee ance depended greatly on selection of the site, colony areas were under water, and there arose time of inoculation, and adequate publicity. considerable danger of a typhoid epidemic. The experience of inoculating in urban areas Thirty centers were set up throughout the was highly encouraging. With adequate plan¬ stricken area for inoculation against typhoid ning, there is no doubt that jet injection can be fever, paratyphoid fever, and cholera. The in¬ successful in treating most of a population's jectors were brought from East Pakistan to aid men, women, and children in a minimum of in the fight. In 4^ days, with only one ma¬ time, whether in an emergency situation or in chine operating, approximately 20,000 persons routine preventive programs. Vol. 75, No. 6, June 1960 473 The hats, or market areas, of Bengal also pro¬ are men and children, it is felt that, by the in¬ vide excellent opportunity to reach the maxi¬ oculation of this great mass of transients, it mum number in the minimum period. These may be possible to break one of the more im¬ weekly markets attract gatherings ranging portant links in the chain of disease, by means from a few hundred to as many as 20,000 of the jet injector, the one instrument by which people, according to their size, location, and im¬ it is possible to inoculate enough of these per¬ portance. In a central location in the hat, even sons quickly. The duration of these hats is only without publicity, it has been comparatively 1 day per week. If the people are not reached easy to inoculate 500 persons an hour with one on that day, they may carry infection through¬ machine. out the Province. The larger markets, such as the Ghior Hat located in Manikganj Subdivision, Dacca Dis¬ Inoculations in Rural Areas trict, provide an excellent opportunity to reach While there remains little doubt that the in¬ many of the people who would be otherwise jectors can be used successfully in places, such comparatively inaccessible and also at the high¬ as municipal areas and markets, where a great est risk.