Defines classes and methods for calculating immunity
- init_immunity(sim, create=True)¶
Initialize immunity matrices with all genotypes and vaccines in the sim
- update_peak_immunity(people, inds, imm_pars, imm_source, offset=None, infection=True)¶
Update immunity level
- This function updates the immunity for individuals when an infection or vaccination occurs.
individuals that are infected and already have immunity from a previous vaccination/infection have their immunity level;
- individuals without prior immunity are assigned an initial level drawn from a distribution. This level
depends on whether the immunity is from a natural infection or from a vaccination (and if so, on the type of vaccine).
people – A people object
inds – Array of people indices
imm_pars – Parameters from which to draw values for quantities like [‘imm_init’] - either sim pars (for natural immunity) or vaccine pars
imm_source – index of either genotype or vaccine where immunity is coming from
Calculate people’s immunity on this timestep from prior infections. As an example, suppose HPV16 and 18 are in the sim, and the cross-immunity matrix is:
- pars[‘immunity’] = np.array([[1., 0.5],
This indicates that people who’ve had HPV18 have 50% protection against getting 16, and people who’ve had 16 have 30% protection against getting 18. Now suppose we have 3 people, whose immunity levels are
- people.imm = np.array([[0.9, 0.0, 0.0],
[0.0, 0.7, 0.0]])
This indicates that person 1 has a prior HPV16 infection, person 2 has a prior HPV18 infection, and person 3 has no history of infection.
- In this function, we take the dot product of pars[‘immunity’] and people.imm to get:
- people.sus_imm = np.array([[0.9 , 0.35, 0. ],
[0.27, 0.7 , 0. ]])
This indicates that the person 1 has high protection against reinfection with HPV16, and some (30% of 90%) protection against infection with HPV18, and so on.
- precompute_waning(t, pars=None)¶
Process functional form and parameters into values:
‘exp_decay’ : exponential decay. Parameters should be init_val and half_life (half_life can be None/nan)
‘linear_decay’: linear decay
A custom function can also be supplied.
length (float) – length of array to return, i.e., for how long waning is calculated
pars (dict) – passed to individual immunity functions
array of length ‘length’ of values
- exp_decay(t, init_val, half_life)¶
Returns an array of length t with values for the immunity at each time step after recovery
- linear_decay(length, init_val, slope)¶
Calculate linear decay
- linear_growth(length, slope)¶
Calculate linear growth