Table 1 Summary of the model parameters.

Constant parameters

Number of age groups

n

10

Number of infectious stages

m

3

Basic reproduction number

R₀

Computed using the method in ref. ⁴⁵

Effective reproduction number

R_e

Computed using the method in ref. ⁴⁵

Probability of transmission per contact

ϵ

Estimated

Reduction in post-lockdown probability of transmission per contact

(1 − ζ₁)

Estimated

Latent period (days)

1/α

Estimated

Infectious period (1/day)

1/γ

Estimated

Contribution of the contact rate after the lockdown

\(f(t)=1/\left[1+{\mathrm{e}}^{-{K}_{1}(t-{t}_{1})}\right]\)

Eq. (2)

Mid-point value of the logistic function (days)

t₁

Estimated

Logistic growth (1/day)

K₁

Estimated

Over-dispersion parameter for the NegBinom distribution for hospitalizations

r

Estimated

Proportion of school contacts

ω

[0, 1], calibrated

Reduction in probability of transmission per contact during relaxation

(1 − ζ₂)

[0, 1], ζ₂ ≥ ζ₁, calibrated

Initial fraction of infected persons

θ

Estimated

Logistic function for relaxation

\(g(t)=1/\left[1+{\mathrm{e}}^{{K}_{2}(t-{t}_{2})}\right]\)

0 ≤ g(t) ≤ 1, calibrated

Force of infection (1/day)

λ_k

Eq. (5)

Hospitalization rate (1/day)

ν_k

Estimated

Susceptibility of age group k relative to age group n^b

β_k

Estimated

General contact rate (1/day)

c_kl

Eqs. (1) and (3)

Contact rate before the pandemic (1/day)

b_kl

¹⁹

Contact rate after the first lockdown (1/day)

a_kl

¹⁹

School contact rate before the pandemic (1/day)

s_kl

^7,20

Population size of age group k

N_k

³⁶