1 00:00:01,920 --> 00:00:04,320 Speaker 1: Welcome to brain Stuff, a production of I Heart Radio, 2 00:00:06,240 --> 00:00:10,680 Speaker 1: Hey brain Stuff, Lauren vogebam Here. Keeping populations of a 3 00:00:10,720 --> 00:00:14,640 Speaker 1: community free from viral disease rests in part on the 4 00:00:14,680 --> 00:00:19,080 Speaker 1: success of herd immunity. Herd immunity rests on the principle 5 00:00:19,239 --> 00:00:22,520 Speaker 1: of safety and numbers. If more people are immune to 6 00:00:22,560 --> 00:00:26,400 Speaker 1: a certain virus, either through vaccination or through already having 7 00:00:26,400 --> 00:00:30,040 Speaker 1: had the disease, then more people in the population, even 8 00:00:30,080 --> 00:00:33,599 Speaker 1: if they themselves aren't immune, are protected from the disease. 9 00:00:34,920 --> 00:00:38,440 Speaker 1: To illustrate this point, let's think about the bowling alleys 10 00:00:38,520 --> 00:00:42,239 Speaker 1: that we're all varyingly aching to return to. Pretend this 11 00:00:42,280 --> 00:00:44,879 Speaker 1: is twenty nineteen and we're packed in for hours, not 12 00:00:44,960 --> 00:00:47,479 Speaker 1: a care in the world besides our frame score and 13 00:00:47,600 --> 00:00:51,200 Speaker 1: access to pizza. Let's say a guy in the first 14 00:00:51,280 --> 00:00:55,200 Speaker 1: lane is there despite having that season's variant of influenza, 15 00:00:55,600 --> 00:00:57,600 Speaker 1: and he passes it along to a woman in the 16 00:00:57,640 --> 00:01:01,320 Speaker 1: second lane. If that woman and immune to that variant 17 00:01:01,360 --> 00:01:04,640 Speaker 1: of influenza, then the disease will likely continue its path 18 00:01:04,920 --> 00:01:07,679 Speaker 1: lane by lane until every person in the bowling alley 19 00:01:07,800 --> 00:01:11,440 Speaker 1: is infected. But if that woman is immune, then the 20 00:01:11,480 --> 00:01:14,640 Speaker 1: disease could well stop with her because the virus has 21 00:01:14,800 --> 00:01:17,280 Speaker 1: nowhere else to go. Assuming that the guy in our 22 00:01:17,319 --> 00:01:21,959 Speaker 1: example didn't have contact with anyone else, by her immunity, 23 00:01:22,280 --> 00:01:25,600 Speaker 1: she protected all the people on subsequent lanes, even if 24 00:01:25,600 --> 00:01:30,720 Speaker 1: they didn't get a flu shot that year. Sounds simple, right, Well, 25 00:01:31,000 --> 00:01:34,840 Speaker 1: it's not that simple. For many of us, chickenpox was 26 00:01:34,880 --> 00:01:38,360 Speaker 1: a routine part of childhood, a minor annoyance but rarely 27 00:01:38,440 --> 00:01:42,240 Speaker 1: life threatening. For that reason, a chickenpox vaccine was met 28 00:01:42,280 --> 00:01:46,800 Speaker 1: with some skepticism when it was introduced, and still there 29 00:01:46,880 --> 00:01:49,840 Speaker 1: was a push in the United States to get children vaccinated, 30 00:01:50,120 --> 00:01:52,760 Speaker 1: and studies have shown that the effort had a tremendous 31 00:01:52,800 --> 00:01:55,760 Speaker 1: impact on the disease and the costs associated with it, 32 00:01:56,280 --> 00:02:00,560 Speaker 1: and chickenpox hospitalizations dropped by a massive scent as of 33 00:02:00,600 --> 00:02:05,000 Speaker 1: twelve compared with the pre vaccine period. During the period 34 00:02:05,040 --> 00:02:07,600 Speaker 1: of two thousand six to twelve, when a second dose 35 00:02:07,680 --> 00:02:11,919 Speaker 1: became recommended, the hospitalization rate declined by another thirty eight percent, 36 00:02:12,240 --> 00:02:16,960 Speaker 1: alleviating more costs all around. Not only does a push 37 00:02:17,000 --> 00:02:20,480 Speaker 1: for a chicken pox vaccine protect child and their classmates, 38 00:02:20,760 --> 00:02:23,079 Speaker 1: you can also protect grandparents who may not have had 39 00:02:23,200 --> 00:02:27,120 Speaker 1: chicken pox. Protecting the elderly is also the idea behind 40 00:02:27,200 --> 00:02:30,160 Speaker 1: another vaccination that many of us line up for every winter, 41 00:02:30,560 --> 00:02:34,160 Speaker 1: the flu shot. Between twelve thousand and sixty one thousand 42 00:02:34,160 --> 00:02:38,280 Speaker 1: Americans have died each year of the flu since of 43 00:02:38,400 --> 00:02:44,040 Speaker 1: those of flu related deaths and fifty of hospitalizations are 44 00:02:44,080 --> 00:02:47,919 Speaker 1: people over the age of sixty five. While the elderly 45 00:02:48,000 --> 00:02:51,040 Speaker 1: are encouraged to get a flu shot, it's actually more 46 00:02:51,080 --> 00:02:55,400 Speaker 1: effective if the herd around them is vaccinated, including caretakers 47 00:02:55,440 --> 00:03:01,720 Speaker 1: and visitors that might include Germany grandchildren. Oh, let's consider polio. 48 00:03:01,880 --> 00:03:05,360 Speaker 1: The success of the polio vaccine demonstrated the benefits of 49 00:03:05,440 --> 00:03:09,160 Speaker 1: using immunization to protect a population, and her immunity can 50 00:03:09,160 --> 00:03:11,960 Speaker 1: be achieved for a whole host of diseases beyond chicken 51 00:03:12,000 --> 00:03:16,200 Speaker 1: pox and the flu, including measles, mumps, and smallpox. And 52 00:03:16,480 --> 00:03:19,880 Speaker 1: while the term herd immunity seems to imply that the 53 00:03:19,960 --> 00:03:23,320 Speaker 1: whole herd should be vaccinated, it actually means that the 54 00:03:23,360 --> 00:03:27,120 Speaker 1: whole herd is protected if a certain percentage is immunized. 55 00:03:27,720 --> 00:03:31,240 Speaker 1: Mathematical models can be used to determine exactly what percentage 56 00:03:31,240 --> 00:03:33,960 Speaker 1: of the population needs to be vaccinated to prevent a 57 00:03:34,040 --> 00:03:40,160 Speaker 1: given communicable disease. For example, if approximately of a population 58 00:03:40,320 --> 00:03:44,960 Speaker 1: is vaccinated against polio, then her immunity is achieved, but 59 00:03:45,320 --> 00:03:50,119 Speaker 1: measles is more contagious than polio of a population needs 60 00:03:50,160 --> 00:03:55,040 Speaker 1: to be vaccinated for her immunity to be achieved. There However, 61 00:03:55,560 --> 00:03:59,040 Speaker 1: just because her immunity is achieved doesn't mean it's completely 62 00:03:59,080 --> 00:04:03,320 Speaker 1: fool proof. Vaccines themselves aren't a hundred percent effective, and 63 00:04:03,400 --> 00:04:06,960 Speaker 1: diseases can still strike those not immune to them. In 64 00:04:07,000 --> 00:04:10,800 Speaker 1: some instances, an immunization is only effective for a few years, 65 00:04:11,160 --> 00:04:13,360 Speaker 1: so the protection may have worn off a majority of 66 00:04:13,400 --> 00:04:16,520 Speaker 1: the herd at the time of an outbreak. The childhood 67 00:04:16,600 --> 00:04:19,760 Speaker 1: vaccinations may only delay the age at which outbreaks occur. 68 00:04:20,480 --> 00:04:23,920 Speaker 1: For example, if a pregnant person contracts the measles, they 69 00:04:24,000 --> 00:04:27,040 Speaker 1: in their unworn baby face far more complications than a 70 00:04:27,120 --> 00:04:33,279 Speaker 1: child who endures the disease. So if vaccines don't work 71 00:04:33,440 --> 00:04:35,719 Speaker 1: or just put off a mass outbreak in the herd, 72 00:04:36,240 --> 00:04:39,159 Speaker 1: do we even need them at all? Some people don't 73 00:04:39,200 --> 00:04:41,200 Speaker 1: think a shot in the arm is worth the good 74 00:04:41,279 --> 00:04:46,120 Speaker 1: of the herd. If the word vaccine strikes fear instead 75 00:04:46,160 --> 00:04:49,000 Speaker 1: of hope in your heart, then you likely came of 76 00:04:49,040 --> 00:04:52,520 Speaker 1: age not in a time dominated by worries about polio, 77 00:04:53,000 --> 00:04:55,600 Speaker 1: but in a time when vaccines make news because of 78 00:04:55,640 --> 00:04:59,960 Speaker 1: side effects ranging from mild irritation to death. The most 79 00:05:00,040 --> 00:05:03,440 Speaker 1: notable example is probably the debate regarding the claim, which 80 00:05:03,480 --> 00:05:06,880 Speaker 1: is not supported by any scientific studies, that an ingredient 81 00:05:06,960 --> 00:05:09,920 Speaker 1: in certain childhood vaccines may have led to an increase 82 00:05:09,960 --> 00:05:13,479 Speaker 1: in autism. These days, in spite of the lack of 83 00:05:13,480 --> 00:05:17,159 Speaker 1: scientific evidence to support a link between vaccines and autism 84 00:05:17,200 --> 00:05:19,840 Speaker 1: and the fact that the ingredient is no longer used 85 00:05:19,839 --> 00:05:24,000 Speaker 1: in most childhood vaccines, some people still have serious doubts 86 00:05:24,040 --> 00:05:27,320 Speaker 1: about whether it's worth protecting herd immunity at the cost 87 00:05:27,360 --> 00:05:32,360 Speaker 1: of exposing children to these supposed risks. That means that 88 00:05:32,480 --> 00:05:35,680 Speaker 1: levels of vaccinations have dropped, particularly in certain parts of 89 00:05:35,720 --> 00:05:40,000 Speaker 1: the United States where exemption from vaccines is granted for religious, philosophical, 90 00:05:40,160 --> 00:05:44,640 Speaker 1: or personal reasons. But socioeconomic factors appear to play a 91 00:05:44,680 --> 00:05:48,400 Speaker 1: bigger role than religious or personal reasons for lack of vaccination. 92 00:05:50,040 --> 00:05:53,040 Speaker 1: C DC summary noted that the percentage of children without 93 00:05:53,080 --> 00:05:56,120 Speaker 1: any vaccines has risen to one point three percent four 94 00:05:56,240 --> 00:06:00,040 Speaker 1: kids born in compared with the two one survey that 95 00:06:00,120 --> 00:06:03,400 Speaker 1: found just zero point three percent of children aged nineteen 96 00:06:03,440 --> 00:06:07,120 Speaker 1: to thirty five months hadn't been vaccinated at all. The 97 00:06:07,160 --> 00:06:10,840 Speaker 1: summary found this was significantly more common among children who 98 00:06:10,839 --> 00:06:15,080 Speaker 1: were uninsured, Medicaid ensured, or who lived in rural areas, 99 00:06:15,600 --> 00:06:19,400 Speaker 1: as seventeen point two percent of unvaccinated children were uninsured, 100 00:06:19,400 --> 00:06:22,279 Speaker 1: for instance, compared with just two point eight percent of 101 00:06:22,320 --> 00:06:26,960 Speaker 1: all children. A study by the Health Testing Centers using 102 00:06:27,040 --> 00:06:31,240 Speaker 1: CDC data found that twenty seven states had kindergarten populations 103 00:06:31,279 --> 00:06:37,000 Speaker 1: with vaccination rates below state targets. As parents who forego 104 00:06:37,120 --> 00:06:40,520 Speaker 1: vaccinations may believe that they can rely on herd immunity 105 00:06:40,600 --> 00:06:44,120 Speaker 1: to protect their children, children who aren't immunized may be 106 00:06:44,240 --> 00:06:48,719 Speaker 1: protected by the children that did get vaccinations. However, as 107 00:06:48,760 --> 00:06:52,400 Speaker 1: parental fears caused vaccination rates to drop, the safety of 108 00:06:52,400 --> 00:06:57,039 Speaker 1: the herd, particularly its weakest members, can become compromised. Some 109 00:06:57,200 --> 00:06:59,920 Speaker 1: children aren't able to be vaccinated because of health reasons 110 00:07:00,080 --> 00:07:03,560 Speaker 1: and truly need to rely on the herd for their immunity. 111 00:07:05,480 --> 00:07:08,320 Speaker 1: Of course, just because science has come a long way 112 00:07:08,360 --> 00:07:12,200 Speaker 1: and addressing major illnesses doesn't mean that large scale outbreaks 113 00:07:12,360 --> 00:07:16,400 Speaker 1: can't happen anymore. The COVID nineteen pandemic has left healthcare 114 00:07:16,480 --> 00:07:20,120 Speaker 1: experts and world leaders grappling with what the best course 115 00:07:20,120 --> 00:07:23,720 Speaker 1: of action is to combat the virus for the long term. 116 00:07:23,920 --> 00:07:27,440 Speaker 1: But while herd immunity is effective for some illnesses, whether 117 00:07:27,480 --> 00:07:30,640 Speaker 1: it's a viable solution for COVID nineteen remains to be seen. 118 00:07:31,960 --> 00:07:35,280 Speaker 1: Evidence to date suggests that herd immunity is likely not 119 00:07:35,440 --> 00:07:39,400 Speaker 1: a realistic option for COVID nineteen. For example, the country 120 00:07:39,400 --> 00:07:42,960 Speaker 1: of Sweden opted to shun social restrictions adopted by much 121 00:07:42,960 --> 00:07:45,320 Speaker 1: of the rest of the world in favor of offering 122 00:07:45,360 --> 00:07:50,360 Speaker 1: optional guidelines to citizens and relying on her immunity. Initial 123 00:07:50,360 --> 00:07:55,120 Speaker 1: reports from April indicated that it hadn't worked out so well, however, 124 00:07:55,440 --> 00:07:58,560 Speaker 1: with Sweden experiencing a COVID nineteen death rate of eight 125 00:07:58,600 --> 00:08:03,600 Speaker 1: percent compared with na bring, Denmark fourcent, and Norway under two, 126 00:08:04,120 --> 00:08:06,600 Speaker 1: both of which enacted greater restrictions from the get go. 127 00:08:08,400 --> 00:08:11,960 Speaker 1: Although the research into and school of thought around COVID 128 00:08:12,040 --> 00:08:15,680 Speaker 1: nineteen changes practically day by day, it stands to reason 129 00:08:15,760 --> 00:08:19,000 Speaker 1: that herd immunity might never be the miracle solution that 130 00:08:19,080 --> 00:08:22,640 Speaker 1: everyone's been praying for. And this is because the virus 131 00:08:22,640 --> 00:08:28,000 Speaker 1: that causes COVID nineteen is probably like other coronaviruses and influenza, 132 00:08:28,240 --> 00:08:32,000 Speaker 1: and that it will mutate over time. When it mutates, 133 00:08:32,080 --> 00:08:35,319 Speaker 1: any antibodies from a prior infection will provide little, if 134 00:08:35,360 --> 00:08:39,400 Speaker 1: any protection. So people who came down with COVID nineteen 135 00:08:40,559 --> 00:08:43,040 Speaker 1: might be protected for a few months to a year 136 00:08:43,120 --> 00:08:49,160 Speaker 1: or two, but lifelong immunity is decidedly unlikely. And don't 137 00:08:49,160 --> 00:08:52,520 Speaker 1: forget that COVID nineteen is about ten times more deadly 138 00:08:52,559 --> 00:08:56,400 Speaker 1: than the flu, and even higher among vulnerable populations like 139 00:08:56,559 --> 00:09:00,120 Speaker 1: the elderly. As a result, it's important that every one 140 00:09:00,160 --> 00:09:03,520 Speaker 1: who's able to receive a COVID nineteen vaccine now sign 141 00:09:03,600 --> 00:09:06,640 Speaker 1: up to receive one, and why our fingers are crossed. 142 00:09:06,679 --> 00:09:09,800 Speaker 1: The vaccine rollout will continue at the safest possible pace, 143 00:09:10,320 --> 00:09:13,640 Speaker 1: and the other treatments will be developed soon. There's a 144 00:09:13,679 --> 00:09:17,880 Speaker 1: possibility that such vaccines will become like flu vaccines, available 145 00:09:17,960 --> 00:09:21,440 Speaker 1: every year to protect you and the herd from new variants. 146 00:09:26,720 --> 00:09:29,320 Speaker 1: Today's episode is based on the article how does herd 147 00:09:29,320 --> 00:09:32,600 Speaker 1: immunity keep a country safe from diseases? On how stuff 148 00:09:32,600 --> 00:09:35,880 Speaker 1: works dot com written by Leah Hoyt and Molly Edmonds. 149 00:09:36,360 --> 00:09:38,720 Speaker 1: Brain Stuff is production of I Heart Radio in partnership 150 00:09:38,760 --> 00:09:40,600 Speaker 1: with how stuff works dot Com and It is produced 151 00:09:40,600 --> 00:09:44,040 Speaker 1: by Tyler Klein. Four more podcasts My Heart Radio, visit 152 00:09:44,080 --> 00:09:46,880 Speaker 1: the iHeart Radio app, Apple podcasts, or wherever you listen 153 00:09:46,920 --> 00:09:47,880 Speaker 1: to your favorite shows.